UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM N-CSR
CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT INVESTMENT COMPANIES
Investment Company Act file number:
811-07332 and 811-08162
Name of Fund:
| BlackRock Funds III |
| BlackRock Cash Funds: Institutional |
| BlackRock Cash Funds: Treasury |
| BlackRock Diversified Equity Fund |
| iShares MSCI Total International Index Fund |
| iShares Russell 1000 Large-Cap Index Fund |
| iShares S&P 500 Index Fund |
| iShares U.S. Aggregate Bond Index Fund |
| Money Market Master Portfolio |
| Treasury Money Market Master Portfolio |
| Diversified Equity Master Portfolio |
| Total International ex U.S. Index Master Portfolio |
| Large Cap Index Master Portfolio |
| S&P 500 Index Master Portfolio |
| U.S. Total Bond Index Master Portfolio |
| International Tilts Master Portfolio |
Fund Address: 100 Bellevue Parkway, Wilmington, DE 19809
Name and address of agent for service: John M. Perlowski, Chief Executive Officer, BlackRock Funds III and Master Investment Portfolio, 50 Hudson Yards, New York, NY 10001
Registrant's telephone number, including area code:
(800) 537-4942
Date of fiscal year end:
12/31/2025
Date of reporting period:
Item 1 — Report to Stockholders
(a) The Report to Shareholders is attached herewith
BlackRock Cash Funds: Institutional
SL Agency Shares | BISXX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about BlackRock Cash Funds: Institutional (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the Money Market Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (888) 204‑3956.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $9(a) | 0.09%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
| Key Fund statistics | |
| $74,180,231,911 | |
| 1 | |
| $54,589,951 | |
| 3.89% | |
| 3.89% |
Past performance is not an indication of future results. Visit blackrock.com for more recent yield information.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Transfer Agent at (888) 204-3956.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates.
BlackRock Cash Funds: Institutional
SL Agency Shares | BISXX
Annual Shareholder Report — December 31, 2025
BISXX-12/25-AR
Annual Shareholder Report — December 31, 2025
What were the Master Portfolio costs for the last year ?
(based on a hypothetical $10,000 investment)
| Master Portfolio name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $ |
| Key Master Portfolio statistics | |
| $ | |
| $ |
What did the Master Portfolio invest in?
(as of December 31, 2025)
| Portfolio composition | ||
| Asset Type | Percent of Net Assets |
|
| % | ||
Additional information
If you wish to view additional information about the Master Portfolio, including but not limited to financial statements and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates.
Money Market Master Portfolio
Annual Shareholder Report — December 31, 2025
12/25-AR
BlackRock Cash Funds: Treasury
Institutional Shares | BRIXX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about BlackRock Cash Funds: Treasury (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the Treasury Money Market Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (888) 204‑3956.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $12(a) | 0.12%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
| Key Fund statistics | |
| $29,836,982,992 | |
| 1 | |
| $15,119,648 | |
| 3.69% | |
| 3.69% |
Past performance is not an indication of future results. Visit blackrock.com for more recent yield information.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Transfer Agent at (888) 204-3956.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates.
BlackRock Cash Funds: Treasury
Institutional Shares | BRIXX
Annual Shareholder Report — December 31, 2025
BRIXX-12/25-AR
BlackRock Cash Funds: Treasury
SL Agency Shares | XTSLA
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about BlackRock Cash Funds: Treasury (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the Treasury Money Market Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (888) 204‑3956.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $9(a) | 0.09%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
| Key Fund statistics | |
| $29,836,982,992 | |
| 1 | |
| $15,119,648 | |
| 3.72% | |
| 3.72% |
Past performance is not an indication of future results. Visit blackrock.com for more recent yield information.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Transfer Agent at (888) 204-3956.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates.
BlackRock Cash Funds: Treasury
SL Agency Shares | XTSLA
Annual Shareholder Report — December 31, 2025
XTSLA-12/25-AR
Annual Shareholder Report — December 31, 2025
What were the Master Portfolio costs for the last year ?
(based on a hypothetical $10,000 investment)
| Master Portfolio name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $ |
| Key Master Portfolio statistics | |
| $ | |
| $ |
What did the Master Portfolio invest in?
(as of December 31, 2025)
| Portfolio composition | ||
| Asset Type | Percent of Net Assets |
|
| % | ||
Additional information
If you wish to view additional information about the Master Portfolio, including but not limited to financial statements and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates.
Treasury Money Market Master Portfolio
Annual Shareholder Report — December 31, 2025
12/25-AR
BlackRock Diversified Equity Fund
Institutional Shares | BDVEX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about BlackRock Diversified Equity Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the Diversified Equity Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 537‑4942.
This report describes changes to the Fund that occurred during the reporting period.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $42(a) | 0.39%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 17.29%.
- For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37%.
What contributed to performance?
Positive contributions to the Fund’s return over the 12-month period were led by Macro Equity positioning which expresses insights on sectors and industries within the mid- and large-cap equity space. The Russell 1000 Enhanced Strategy and Russell 2000 Enhanced Strategy, which use a bottom-up approach to identify investment opportunities within the U.S. large-cap and small-cap markets, respectively, also added materially to performance.
What detracted from performance?
The Emerging Markets Enhanced Strategy, which utilizes a bottom-up approach to identify investment opportunities within emerging markets, detracted on an absolute basis over the trailing one-year period.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 17.29 | % | 13.79 | % | 14.65 | % | |
| 17.37 | 13.59 | 14.59 |
| Key Fund statistics | |
| $1,201,712,418 | |
| 1 | |
| $1,576,054 | |
| 123% |
Performance shown prior to the Institutional Shares inception date of September 19, 2023 is based upon the performance of the Master Portfolio in which the Fund invests all of its assets, adjusted to reflect the Institutional Shares fees and operating expenses.
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Material Fund changes
This is a summary of planned changes to the Fund since December 31, 2024. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after December 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 537-4942.
On February 19, 2026, the Fund’s Board approved a change in the name of the Fund to BlackRock Diversified Equity Alpha Fund. The Fund (through its investment in the Master Portfolio) will invest, under normal circumstances, at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in equity securities and derivatives that provide investment exposure to such securities or to one or more risk factors associated with such securities These changes are expected to become effective on or about April 28, 2026.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 537-4942.
The Fund is not sponsored, endorsed, issued, sold, or promoted by FTSE International Limited and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
BlackRock Diversified Equity Fund
Institutional Shares | BDVEX
Annual Shareholder Report — December 31, 2025
BDVEX-12/25-AR
Annual Shareholder Report — December 31, 2025
This report describes changes to the Master Portfolio that occurred during the reporting period.
What were the Master Portfolio costs for the last year ?
(based on a hypothetical $10,000 investment)
| Master Portfolio name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $ |
| Key Master Portfolio statistics | |
| $ | |
| $ | |
What did the Master Portfolio invest in?
(as of December 31, 2025)
| Sector allocation | ||
| Sector(a) | Percent of Net Assets |
|
| % | ||
| ( |
) | |
| Ten largest holdings | ||
| Security(b) | Percent of Net Assets |
|
| % | ||
| |
| |
Material Master Portfolio changes
This is a summary of planned changes to the Master Portfolio since December 31, 2024.
Additional information
If you wish to view additional information about the Master Portfolio, including but not limited to financial statements and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
Diversified Equity Master Portfolio
Annual Shareholder Report — December 31, 2025
12/25-AR
iShares MSCI Total International Index Fund
Institutional Shares | BDOIX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares MSCI Total International Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the Total International ex U.S. Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $16(a) | 0.14%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 32.58%.
- For the same period, the Fund’s benchmark, the MSCI ACWI ex USA Index (Net) returned 32.39%.
In 2025, European equities started the year in positive territory despite rising United States (“U.S.”) tariff pressures. The European Central Bank (“ECB”) cut rates by 25 basis points in both January 2025 and March 2025 to mitigate recession risks, with President Lagarde noting that euro area growth would likely remain weak amid persistent inflationary pressures. European Union finance ministers emphasized unity and deeper market integration to offset tariff‑related disruptions. In Japan, equities were volatile throughout the first quarter, and the Nikkei 225 Index ended the period in negative territory as investors grew cautious about the new U.S. administration’s tougher tariff stance and its implications for corporate earnings and broader economic conditions.
European equities continued to advance in the second quarter of 2025, supported by resilient investor sentiment despite slower economic momentum and persistent global trade tensions. The ECB held rates steady following the earlier cuts and reiterated its commitment to supporting growth as inflation remained elevated. Policymakers also highlighted the importance of fiscal discipline and reinforced the need for European Union cohesion. Japan experienced a strong rebound during the second quarter, with the Nikkei 225 Index closing near all‑time highs on June 30, 2025, driven by new stimulus measures and a more stable Japanese Yen, although uncertainties around export demand and supply chain pressures continued to weigh on corporate outlooks.
Europe remained resilient during the third quarter of 2025, supported by firm domestic demand and a healthy labor market. The ECB maintained rates at 2.0% in both July 2025 and September 2025, pausing its year‑long easing cycle as inflation hovered near target despite a slight uptick in September. Japanese equities extended their gains through the third quarter, supported by easing trade tensions, increasing investor interest in artificial intelligence (“AI”), and improved sentiment tied to anticipated political leadership changes. The Bank of Japan (“BOJ”) kept rates unchanged at 0.5%, though some policymakers signaled openness to future increases.
European equities continued to rise in the fourth quarter of 2025, even as global volatility driven by AI‑related market concerns briefly unsettled sentiment before rebound into year‑end. The ECB retained rates at 2.0% in both October 2025 and December 2025, citing better‑than‑expected eurozone growth and inflation trending close to target while maintaining a cautious, data‑dependent stance. Japan again delivered strong equity performance in the fourth quarter, supported by above‑target inflation, notable wage growth, sustained AI‑driven enthusiasm, and a weak yen that boosted export competitiveness. The BOJ held rates steady in October 2025 and raised them in December 2025 to 0.75%, reflecting growing confidence in Japan’s improving economic backdrop despite continuing global trade uncertainty.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 32.58 | % | 7.66 | % | 8.31 | % | |
| 32.39 | 7.91 | 8.41 |
| Key Fund statistics | |
| $2,168,181,336 | |
| 1 | |
| $586,442 | |
| 13% |
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by MSCI Inc. and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares MSCI Total International Index Fund
Institutional Shares | BDOIX
Annual Shareholder Report — December 31, 2025
BDOIX-12/25-AR
iShares MSCI Total International Index Fund
Investor A Shares | BDOAX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares MSCI Total International Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the Total International ex U.S. Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $46(a) | 0.40%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 32.21%.
- For the same period, the Fund’s benchmark, the MSCI ACWI ex USA Index (Net) returned 32.39%.
In 2025, European equities started the year in positive territory despite rising United States (“U.S.”) tariff pressures. The European Central Bank (“ECB”) cut rates by 25 basis points in both January 2025 and March 2025 to mitigate recession risks, with President Lagarde noting that euro area growth would likely remain weak amid persistent inflationary pressures. European Union finance ministers emphasized unity and deeper market integration to offset tariff‑related disruptions. In Japan, equities were volatile throughout the first quarter, and the Nikkei 225 Index ended the period in negative territory as investors grew cautious about the new U.S. administration’s tougher tariff stance and its implications for corporate earnings and broader economic conditions.
European equities continued to advance in the second quarter of 2025, supported by resilient investor sentiment despite slower economic momentum and persistent global trade tensions. The ECB held rates steady following the earlier cuts and reiterated its commitment to supporting growth as inflation remained elevated. Policymakers also highlighted the importance of fiscal discipline and reinforced the need for European Union cohesion. Japan experienced a strong rebound during the second quarter, with the Nikkei 225 Index closing near all‑time highs on June 30, 2025, driven by new stimulus measures and a more stable Japanese Yen, although uncertainties around export demand and supply chain pressures continued to weigh on corporate outlooks.
Europe remained resilient during the third quarter of 2025, supported by firm domestic demand and a healthy labor market. The ECB maintained rates at 2.0% in both July 2025 and September 2025, pausing its year‑long easing cycle as inflation hovered near target despite a slight uptick in September. Japanese equities extended their gains through the third quarter, supported by easing trade tensions, increasing investor interest in artificial intelligence (“AI”), and improved sentiment tied to anticipated political leadership changes. The Bank of Japan (“BOJ”) kept rates unchanged at 0.5%, though some policymakers signaled openness to future increases.
European equities continued to rise in the fourth quarter of 2025, even as global volatility driven by AI‑related market concerns briefly unsettled sentiment before rebound into year‑end. The ECB retained rates at 2.0% in both October 2025 and December 2025, citing better‑than‑expected eurozone growth and inflation trending close to target while maintaining a cautious, data‑dependent stance. Japan again delivered strong equity performance in the fourth quarter, supported by above‑target inflation, notable wage growth, sustained AI‑driven enthusiasm, and a weak yen that boosted export competitiveness. The BOJ held rates steady in October 2025 and raised them in December 2025 to 0.75%, reflecting growing confidence in Japan’s improving economic backdrop despite continuing global trade uncertainty.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 32.21 | % | 7.37 | % | 8.03 | % | |
| 32.39 | 7.91 | 8.41 |
| Key Fund statistics | |
| $2,168,181,336 | |
| 1 | |
| $586,442 | |
| 13% |
Average annual total returns reflect reductions for service fees.
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by MSCI Inc. and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares MSCI Total International Index Fund
Investor A Shares | BDOAX
Annual Shareholder Report — December 31, 2025
BDOAX-12/25-AR
iShares MSCI Total International Index Fund
Class K Shares | BDOKX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares MSCI Total International Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the Total International ex U.S. Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $10(a) | 0.09%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 32.57%.
- For the same period, the Fund’s benchmark, the MSCI ACWI ex USA Index (Net) returned 32.39%.
In 2025, European equities started the year in positive territory despite rising United States (“U.S.”) tariff pressures. The European Central Bank (“ECB”) cut rates by 25 basis points in both January 2025 and March 2025 to mitigate recession risks, with President Lagarde noting that euro area growth would likely remain weak amid persistent inflationary pressures. European Union finance ministers emphasized unity and deeper market integration to offset tariff‑related disruptions. In Japan, equities were volatile throughout the first quarter, and the Nikkei 225 Index ended the period in negative territory as investors grew cautious about the new U.S. administration’s tougher tariff stance and its implications for corporate earnings and broader economic conditions.
European equities continued to advance in the second quarter of 2025, supported by resilient investor sentiment despite slower economic momentum and persistent global trade tensions. The ECB held rates steady following the earlier cuts and reiterated its commitment to supporting growth as inflation remained elevated. Policymakers also highlighted the importance of fiscal discipline and reinforced the need for European Union cohesion. Japan experienced a strong rebound during the second quarter, with the Nikkei 225 Index closing near all‑time highs on June 30, 2025, driven by new stimulus measures and a more stable Japanese Yen, although uncertainties around export demand and supply chain pressures continued to weigh on corporate outlooks.
Europe remained resilient during the third quarter of 2025, supported by firm domestic demand and a healthy labor market. The ECB maintained rates at 2.0% in both July 2025 and September 2025, pausing its year‑long easing cycle as inflation hovered near target despite a slight uptick in September. Japanese equities extended their gains through the third quarter, supported by easing trade tensions, increasing investor interest in artificial intelligence (“AI”), and improved sentiment tied to anticipated political leadership changes. The Bank of Japan (“BOJ”) kept rates unchanged at 0.5%, though some policymakers signaled openness to future increases.
European equities continued to rise in the fourth quarter of 2025, even as global volatility driven by AI‑related market concerns briefly unsettled sentiment before rebound into year‑end. The ECB retained rates at 2.0% in both October 2025 and December 2025, citing better‑than‑expected eurozone growth and inflation trending close to target while maintaining a cautious, data‑dependent stance. Japan again delivered strong equity performance in the fourth quarter, supported by above‑target inflation, notable wage growth, sustained AI‑driven enthusiasm, and a weak yen that boosted export competitiveness. The BOJ held rates steady in October 2025 and raised them in December 2025 to 0.75%, reflecting growing confidence in Japan’s improving economic backdrop despite continuing global trade uncertainty.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 32.57 | % | 7.71 | % | 8.36 | % | |
| 32.39 | 7.91 | 8.41 |
| Key Fund statistics | |
| $2,168,181,336 | |
| 1 | |
| $586,442 | |
| 13% |
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by MSCI Inc. and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares MSCI Total International Index Fund
Class K Shares | BDOKX
Annual Shareholder Report — December 31, 2025
BDOKX-12/25-AR
Annual Shareholder Report — December 31, 2025
What were the Master Portfolio costs for the last year ?
(based on a hypothetical $10,000 investment)
| Master Portfolio name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $ |
| Key Master Portfolio statistics | |
| $ | |
| $ | |
What did the Master Portfolio invest in?
(as of December 31, 2025)
| Geographic allocation | ||
| Country/Geographic Region | Percent of Net Assets |
|
| % | ||
| ( |
) | |
| Ten largest holdings | ||
| Security(a) | Percent of Net Assets |
|
| % | ||
| |
| |
Additional information
If you wish to view additional information about the Master Portfolio, including but not limited to financial statements and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
Total International ex U.S. Index Master Portfolio
Annual Shareholder Report — December 31, 2025
12/25-AR
iShares Russell 1000 Large-Cap Index Fund
Institutional Shares | BRGNX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares Russell 1000 Large-Cap Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the Large Cap Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
This report describes changes to the Fund that occurred during the reporting period.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $12(a) | 0.11%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 17.21%.
- For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37%.
Domestic United States (“U.S.”) equities ended the first quarter in negative territory as the U.S. administration introduced broad shifts in global trade policy, including reciprocal tariffs that elevated economic uncertainty and pushed U.S. equity markets briefly into correction territory. Markets remained highly sensitive to tariff announcements expected in April 2025. The Federal Open Market Committee (“FOMC”) held interest rates at 4.25%–4.50% in January and reaffirmed expectations for two rate cuts in 2025, though policymakers maintained a firmly data‑dependent stance given persistent inflation and a still‑resilient labor market.
U.S. equities rebounded in the second quarter and finished in positive territory as volatility eased following an early‑April 2025 spike that drove the Chicago Board Options Exchange Volatility Index (“VIX”) to multi‑year highs. Sentiment improved after the U.S. administration announced a 90‑day pause on most proposed tariffs, temporarily alleviating trade pressures ahead of the July 2025 deadline. On April 9th, just after significant market volatility and rising economic concerns, President Trump and the White House suspended additional tariffs above a 10% base rate for most countries, with the pause set to expire in early July.
The FOMC kept rates unchanged at 4.25%–4.50% in both May and June, noting cautious progress toward the 2% inflation target. Strong corporate earnings and continued enthusiasm around artificial intelligence (“AI”) supported equity gains even as reciprocal tariffs on more than 60 countries, while additional trade deals were being agreed on, China tariffs were paused to allow for negotiations to continue. This added uncertainty to longer‑term economic forecasts.
U.S. equities continued to advance through the third quarter, supported by solid earnings momentum and receding market volatility. The FOMC maintained its data‑driven approach, holding rates steady in July 2025 and delivering the first rate cut of the year in September, lowering the target range to 4.00%–4.25%. The committee cited slowing job growth and a meaningful decline in hiring as key drivers of the “risk‑management” cut, while tariff‑related inflation pressures remained a central consideration for future policy decisions. Despite mixed macroeconomic signals, investor sentiment remained broadly constructive.
Equity markets posted modest gains in the fourth quarter amid elevated volatility driven by concerns about an emerging AI bubble. Fears escalated throughout the quarter with investors worrying about lofty valuations and heavy capital expenditures, weighing on sentiment before stabilizing on signs of real revenue growth. The longest U.S. government shutdown in history, lasting 43 days, had a muted impact on markets, while renewed tariff negotiations with China in October 2025 added another layer of uncertainty. Labor conditions weakened as unemployment rose to 4.6% in November and inflation remained above the Federal Reserve’s 2% target, prompting the FOMC to cut rates by 25 bps in both October and December, ending the year with a 3.50%–3.75% target range and a continued commitment to data dependent policymaking heading into 2026.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 17.21 | % | 13.48 | % | 14.46 | % | |
| 17.37 | 13.59 | 14.59 |
| Key Fund statistics | |
| $1,848,151,933 | |
| 1 | |
| $491,834 | |
| 12% |
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Material Fund changes
This is a summary of certain changes to the Fund since December 31, 2024. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after December 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective November 20, 2025, the Fund updated its investment policy to indicate that it intends to be “diversified,” as defined in the Investment Company Act of 1940, as amended, in approximately the same proportion as its underlying index, the Russell 1000® Index (the "Underlying Index"), is diversified. Shareholder approval will not be sought if the Fund crosses from diversified to non-diversified status due solely to a change in the relative market capitalization or index weighting of the constituents of its Underlying Index. The Fund's Principal Investment Strategies were revised to reflect these updates.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by FTSE International Limited and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares Russell 1000 Large-Cap Index Fund
Institutional Shares | BRGNX
Annual Shareholder Report — December 31, 2025
BRGNX-12/25-AR
iShares Russell 1000 Large-Cap Index Fund
Investor A Shares | BRGAX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares Russell 1000 Large-Cap Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the Large Cap Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
This report describes changes to the Fund that occurred during the reporting period.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $39(a) | 0.36%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 16.94%.
- For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37%.
Domestic United States (“U.S.”) equities ended the first quarter in negative territory as the U.S. administration introduced broad shifts in global trade policy, including reciprocal tariffs that elevated economic uncertainty and pushed U.S. equity markets briefly into correction territory. Markets remained highly sensitive to tariff announcements expected in April 2025. The Federal Open Market Committee (“FOMC”) held interest rates at 4.25%–4.50% in January and reaffirmed expectations for two rate cuts in 2025, though policymakers maintained a firmly data‑dependent stance given persistent inflation and a still‑resilient labor market.
U.S. equities rebounded in the second quarter and finished in positive territory as volatility eased following an early‑April 2025 spike that drove the Chicago Board Options Exchange Volatility Index (“VIX”) to multi‑year highs. Sentiment improved after the U.S. administration announced a 90‑day pause on most proposed tariffs, temporarily alleviating trade pressures ahead of the July 2025 deadline. On April 9th, just after significant market volatility and rising economic concerns, President Trump and the White House suspended additional tariffs above a 10% base rate for most countries, with the pause set to expire in early July.
The FOMC kept rates unchanged at 4.25%–4.50% in both May and June, noting cautious progress toward the 2% inflation target. Strong corporate earnings and continued enthusiasm around artificial intelligence (“AI”) supported equity gains even as reciprocal tariffs on more than 60 countries, while additional trade deals were being agreed on, China tariffs were paused to allow for negotiations to continue. This added uncertainty to longer‑term economic forecasts.
U.S. equities continued to advance through the third quarter, supported by solid earnings momentum and receding market volatility. The FOMC maintained its data‑driven approach, holding rates steady in July 2025 and delivering the first rate cut of the year in September, lowering the target range to 4.00%–4.25%. The committee cited slowing job growth and a meaningful decline in hiring as key drivers of the “risk‑management” cut, while tariff‑related inflation pressures remained a central consideration for future policy decisions. Despite mixed macroeconomic signals, investor sentiment remained broadly constructive.
Equity markets posted modest gains in the fourth quarter amid elevated volatility driven by concerns about an emerging AI bubble. Fears escalated throughout the quarter with investors worrying about lofty valuations and heavy capital expenditures, weighing on sentiment before stabilizing on signs of real revenue growth. The longest U.S. government shutdown in history, lasting 43 days, had a muted impact on markets, while renewed tariff negotiations with China in October 2025 added another layer of uncertainty. Labor conditions weakened as unemployment rose to 4.6% in November and inflation remained above the Federal Reserve’s 2% target, prompting the FOMC to cut rates by 25 bps in both October and December, ending the year with a 3.50%–3.75% target range and a continued commitment to data dependent policymaking heading into 2026.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 16.94 | % | 13.20 | % | 14.16 | % | |
| 17.37 | 13.59 | 14.59 |
| Key Fund statistics | |
| $1,848,151,933 | |
| 1 | |
| $491,834 | |
| 12% |
Average annual total returns reflect reductions for service fees.
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Material Fund changes
This is a summary of certain changes to the Fund since December 31, 2024. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after December 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective November 20, 2025, the Fund updated its investment policy to indicate that it intends to be “diversified,” as defined in the Investment Company Act of 1940, as amended, in approximately the same proportion as its underlying index, the Russell 1000® Index (the "Underlying Index"), is diversified. Shareholder approval will not be sought if the Fund crosses from diversified to non-diversified status due solely to a change in the relative market capitalization or index weighting of the constituents of its Underlying Index. The Fund's Principal Investment Strategies were revised to reflect these updates.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by FTSE International Limited and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares Russell 1000 Large-Cap Index Fund
Investor A Shares | BRGAX
Annual Shareholder Report — December 31, 2025
BRGAX-12/25-AR
iShares Russell 1000 Large-Cap Index Fund
Class K Shares | BRGKX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares Russell 1000 Large-Cap Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the Large Cap Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
This report describes changes to the Fund that occurred during the reporting period.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $7(a) | 0.06%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 17.27%.
- For the same period, the Fund’s benchmark, the Russell 1000® Index returned 17.37%.
Domestic United States (“U.S.”) equities ended the first quarter in negative territory as the U.S. administration introduced broad shifts in global trade policy, including reciprocal tariffs that elevated economic uncertainty and pushed U.S. equity markets briefly into correction territory. Markets remained highly sensitive to tariff announcements expected in April 2025. The Federal Open Market Committee (“FOMC”) held interest rates at 4.25%–4.50% in January and reaffirmed expectations for two rate cuts in 2025, though policymakers maintained a firmly data‑dependent stance given persistent inflation and a still‑resilient labor market.
U.S. equities rebounded in the second quarter and finished in positive territory as volatility eased following an early‑April 2025 spike that drove the Chicago Board Options Exchange Volatility Index (“VIX”) to multi‑year highs. Sentiment improved after the U.S. administration announced a 90‑day pause on most proposed tariffs, temporarily alleviating trade pressures ahead of the July 2025 deadline. On April 9th, just after significant market volatility and rising economic concerns, President Trump and the White House suspended additional tariffs above a 10% base rate for most countries, with the pause set to expire in early July.
The FOMC kept rates unchanged at 4.25%–4.50% in both May and June, noting cautious progress toward the 2% inflation target. Strong corporate earnings and continued enthusiasm around artificial intelligence (“AI”) supported equity gains even as reciprocal tariffs on more than 60 countries, while additional trade deals were being agreed on, China tariffs were paused to allow for negotiations to continue. This added uncertainty to longer‑term economic forecasts.
U.S. equities continued to advance through the third quarter, supported by solid earnings momentum and receding market volatility. The FOMC maintained its data‑driven approach, holding rates steady in July 2025 and delivering the first rate cut of the year in September, lowering the target range to 4.00%–4.25%. The committee cited slowing job growth and a meaningful decline in hiring as key drivers of the “risk‑management” cut, while tariff‑related inflation pressures remained a central consideration for future policy decisions. Despite mixed macroeconomic signals, investor sentiment remained broadly constructive.
Equity markets posted modest gains in the fourth quarter amid elevated volatility driven by concerns about an emerging AI bubble. Fears escalated throughout the quarter with investors worrying about lofty valuations and heavy capital expenditures, weighing on sentiment before stabilizing on signs of real revenue growth. The longest U.S. government shutdown in history, lasting 43 days, had a muted impact on markets, while renewed tariff negotiations with China in October 2025 added another layer of uncertainty. Labor conditions weakened as unemployment rose to 4.6% in November and inflation remained above the Federal Reserve’s 2% target, prompting the FOMC to cut rates by 25 bps in both October and December, ending the year with a 3.50%–3.75% target range and a continued commitment to data dependent policymaking heading into 2026.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 17.27 | % | 13.54 | % | 14.51 | % | |
| 17.37 | 13.59 | 14.59 |
| Key Fund statistics | |
| $1,848,151,933 | |
| 1 | |
| $491,834 | |
| 12% |
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Material Fund changes
This is a summary of certain changes to the Fund since December 31, 2024. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after December 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective November 20, 2025, the Fund updated its investment policy to indicate that it intends to be “diversified,” as defined in the Investment Company Act of 1940, as amended, in approximately the same proportion as its underlying index, the Russell 1000® Index (the "Underlying Index"), is diversified. Shareholder approval will not be sought if the Fund crosses from diversified to non-diversified status due solely to a change in the relative market capitalization or index weighting of the constituents of its Underlying Index. The Fund's Principal Investment Strategies were revised to reflect these updates.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by FTSE International Limited and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares Russell 1000 Large-Cap Index Fund
Class K Shares | BRGKX
Annual Shareholder Report — December 31, 2025
BRGKX-12/25-AR
Annual Shareholder Report — December 31, 2025
What were the Master Portfolio costs for the last year ?
(based on a hypothetical $10,000 investment)
| Master Portfolio name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $ |
| Key Master Portfolio statistics | |
| $ | |
| $ | |
What did the Master Portfolio invest in?
(as of December 31, 2025)
| Sector allocation | ||
| Sector(a) | Percent of Net Assets |
|
| % | ||
| ( |
) | |
| Ten largest holdings | ||
| Security(b) | Percent of Net Assets |
|
| % | ||
| |
| |
Additional information
If you wish to view additional information about the Master Portfolio, including but not limited to financial statements and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
Large Cap Index Master Portfolio
Annual Shareholder Report — December 31, 2025
12/25-AR
iShares S&P 500 Index Fund
Institutional Shares | BSPIX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares S&P 500 Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the S&P 500 Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
This report describes changes to the Fund that occurred during the reporting period.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $11(a) | 0.10%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 17.75%.
- For the same period, the Fund’s benchmark, the S&P 500® Index returned 17.88%.
Domestic United States (“U.S.”) equities ended the first quarter in negative territory as the U.S. administration introduced broad shifts in global trade policy, including reciprocal tariffs that elevated economic uncertainty and pushed the S&P 500 briefly into correction territory. Markets remained highly sensitive to tariff announcements expected in April 2025. The Federal Open Market Committee (“FOMC”) held interest rates at 4.25%–4.50% in January and reaffirmed expectations for two rate cuts in 2025, though policymakers maintained a firmly data–dependent stance given persistent inflation and a still–resilient labor market.
U.S. equities rebounded in the second quarter and finished in positive territory as volatility eased following an early–April 2025 spike that drove the Chicago Board Options Exchange Volatility Index (“VIX”) to multi–year highs. Sentiment improved after the U.S. administration announced a 90–day pause on most proposed tariffs, temporarily alleviating trade pressures ahead of the July 2025 deadline. On April 9th, just after significant market volatility and rising economic concerns, President Trump and the White House suspended additional tariffs above a 10% base rate for most countries, with the pause set to expire in early July.
The FOMC kept rates unchanged at 4.25%–4.50% in both May and June, noting cautious progress toward the 2% inflation target. Strong corporate earnings and continued enthusiasm around artificial intelligence (“AI”) supported equity gains even as reciprocal tariffs on more than 60 countries, while additional trade deals were being agreed on, China tariffs were paused to allow for negotiations to continue. This added uncertainty to longer term economic forecasts.
U.S. equities continued to advance through the third quarter, supported by solid earnings momentum and receding market volatility. The FOMC maintained its data driven approach, holding rates steady in July 2025 and delivering the first rate cut of the year in September, lowering the target range to 4.00%–4.25%. The committee cited slowing job growth and a meaningful decline in hiring as key drivers of the “risk–management” cut, while tariff related inflation pressures remained a central consideration for future policy decisions. Despite mixed macroeconomic signals, investor sentiment remained broadly constructive.
Equity markets posted modest gains in the fourth quarter amid elevated volatility driven by concerns about an emerging AI bubble. Fears escalated throughout the quarter with investors worrying about lofty valuations and heavy capital expenditures, weighing on sentiment before stabilizing on signs of real revenue growth. The longest U.S. government shutdown in history, lasting 43 days, had a muted impact on markets, while renewed tariff negotiations with China in October 2025 added another layer of uncertainty. Labor conditions weakened as unemployment rose to 4.6% in November and inflation remained above the Federal Reserve’s 2% target, prompting the FOMC to cut rates by 25 bps in both October and December, ending the year with a 3.50%–3.75% target range and a continued commitment to data dependent policymaking heading into 2026.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 17.75 | % | 14.30 | % | 14.71 | % | |
| 17.88 | 14.42 | 14.82 |
| Key Fund statistics | |
| $53,488,256,039 | |
| 1 | |
| $4,758,005 | |
| 14% |
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Material Fund changes
This is a summary of certain changes to the Fund since December 31, 2024. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after December 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective November 20, 2025, the Fund revised its principal investment policies to reflect that the Fund intends to be diversified in approximately the same proportion as the S&P 500 Index (the "Underlying Index") is diversified. The Fund may become “non‑diversified,” as defined in the Investment Company Act of 1940, as amended, solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by S&P Dow Jones Indices and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares S&P 500 Index Fund
Institutional Shares | BSPIX
Annual Shareholder Report — December 31, 2025
BSPIX-12/25-AR
iShares S&P 500 Index Fund
Service Shares | BSPSX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares S&P 500 Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the S&P 500 Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
This report describes changes to the Fund that occurred during the reporting period.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $24(a) | 0.22%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Service Shares returned 17.60%.
- For the same period, the Fund’s benchmark, the S&P 500® Index returned 17.88%.
Domestic United States (“U.S.”) equities ended the first quarter in negative territory as the U.S. administration introduced broad shifts in global trade policy, including reciprocal tariffs that elevated economic uncertainty and pushed the S&P 500 briefly into correction territory. Markets remained highly sensitive to tariff announcements expected in April 2025. The Federal Open Market Committee (“FOMC”) held interest rates at 4.25%–4.50% in January and reaffirmed expectations for two rate cuts in 2025, though policymakers maintained a firmly data–dependent stance given persistent inflation and a still–resilient labor market.
U.S. equities rebounded in the second quarter and finished in positive territory as volatility eased following an early–April 2025 spike that drove the Chicago Board Options Exchange Volatility Index (“VIX”) to multi–year highs. Sentiment improved after the U.S. administration announced a 90–day pause on most proposed tariffs, temporarily alleviating trade pressures ahead of the July 2025 deadline. On April 9th, just after significant market volatility and rising economic concerns, President Trump and the White House suspended additional tariffs above a 10% base rate for most countries, with the pause set to expire in early July.
The FOMC kept rates unchanged at 4.25%–4.50% in both May and June, noting cautious progress toward the 2% inflation target. Strong corporate earnings and continued enthusiasm around artificial intelligence (“AI”) supported equity gains even as reciprocal tariffs on more than 60 countries, while additional trade deals were being agreed on, China tariffs were paused to allow for negotiations to continue. This added uncertainty to longer term economic forecasts.
U.S. equities continued to advance through the third quarter, supported by solid earnings momentum and receding market volatility. The FOMC maintained its data driven approach, holding rates steady in July 2025 and delivering the first rate cut of the year in September, lowering the target range to 4.00%–4.25%. The committee cited slowing job growth and a meaningful decline in hiring as key drivers of the “risk–management” cut, while tariff related inflation pressures remained a central consideration for future policy decisions. Despite mixed macroeconomic signals, investor sentiment remained broadly constructive.
Equity markets posted modest gains in the fourth quarter amid elevated volatility driven by concerns about an emerging AI bubble. Fears escalated throughout the quarter with investors worrying about lofty valuations and heavy capital expenditures, weighing on sentiment before stabilizing on signs of real revenue growth. The longest U.S. government shutdown in history, lasting 43 days, had a muted impact on markets, while renewed tariff negotiations with China in October 2025 added another layer of uncertainty. Labor conditions weakened as unemployment rose to 4.6% in November and inflation remained above the Federal Reserve’s 2% target, prompting the FOMC to cut rates by 25 bps in both October and December, ending the year with a 3.50%–3.75% target range and a continued commitment to data dependent policymaking heading into 2026.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 17.60 | % | 14.16 | % | 14.57 | % | |
| 17.88 | 14.42 | 14.82 |
| Key Fund statistics | |
| $53,488,256,039 | |
| 1 | |
| $4,758,005 | |
| 14% |
Average annual total returns reflect reductions for service fees.
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Material Fund changes
This is a summary of certain changes to the Fund since December 31, 2024. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after December 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective November 20, 2025, the Fund revised its principal investment policies to reflect that the Fund intends to be diversified in approximately the same proportion as the S&P 500 Index (the "Underlying Index") is diversified. The Fund may become “non‑diversified,” as defined in the Investment Company Act of 1940, as amended, solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by S&P Dow Jones Indices and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares S&P 500 Index Fund
Service Shares | BSPSX
Annual Shareholder Report — December 31, 2025
BSPSX-12/25-AR
iShares S&P 500 Index Fund
Investor A Shares | BSPAX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares S&P 500 Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the S&P 500 Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
This report describes changes to the Fund that occurred during the reporting period.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $38(a) | 0.35%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 17.45%.
- For the same period, the Fund’s benchmark, the S&P 500® Index returned 17.88%.
Domestic United States (“U.S.”) equities ended the first quarter in negative territory as the U.S. administration introduced broad shifts in global trade policy, including reciprocal tariffs that elevated economic uncertainty and pushed the S&P 500 briefly into correction territory. Markets remained highly sensitive to tariff announcements expected in April 2025. The Federal Open Market Committee (“FOMC”) held interest rates at 4.25%–4.50% in January and reaffirmed expectations for two rate cuts in 2025, though policymakers maintained a firmly data–dependent stance given persistent inflation and a still–resilient labor market.
U.S. equities rebounded in the second quarter and finished in positive territory as volatility eased following an early–April 2025 spike that drove the Chicago Board Options Exchange Volatility Index (“VIX”) to multi–year highs. Sentiment improved after the U.S. administration announced a 90–day pause on most proposed tariffs, temporarily alleviating trade pressures ahead of the July 2025 deadline. On April 9th, just after significant market volatility and rising economic concerns, President Trump and the White House suspended additional tariffs above a 10% base rate for most countries, with the pause set to expire in early July.
The FOMC kept rates unchanged at 4.25%–4.50% in both May and June, noting cautious progress toward the 2% inflation target. Strong corporate earnings and continued enthusiasm around artificial intelligence (“AI”) supported equity gains even as reciprocal tariffs on more than 60 countries, while additional trade deals were being agreed on, China tariffs were paused to allow for negotiations to continue. This added uncertainty to longer term economic forecasts.
U.S. equities continued to advance through the third quarter, supported by solid earnings momentum and receding market volatility. The FOMC maintained its data driven approach, holding rates steady in July 2025 and delivering the first rate cut of the year in September, lowering the target range to 4.00%–4.25%. The committee cited slowing job growth and a meaningful decline in hiring as key drivers of the “risk–management” cut, while tariff related inflation pressures remained a central consideration for future policy decisions. Despite mixed macroeconomic signals, investor sentiment remained broadly constructive.
Equity markets posted modest gains in the fourth quarter amid elevated volatility driven by concerns about an emerging AI bubble. Fears escalated throughout the quarter with investors worrying about lofty valuations and heavy capital expenditures, weighing on sentiment before stabilizing on signs of real revenue growth. The longest U.S. government shutdown in history, lasting 43 days, had a muted impact on markets, while renewed tariff negotiations with China in October 2025 added another layer of uncertainty. Labor conditions weakened as unemployment rose to 4.6% in November and inflation remained above the Federal Reserve’s 2% target, prompting the FOMC to cut rates by 25 bps in both October and December, ending the year with a 3.50%–3.75% target range and a continued commitment to data dependent policymaking heading into 2026.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 17.45 | % | 14.01 | % | 14.42 | % | |
| 17.88 | 14.42 | 14.82 |
| Key Fund statistics | |
| $53,488,256,039 | |
| 1 | |
| $4,758,005 | |
| 14% |
Average annual total returns reflect reductions for service fees.
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Material Fund changes
This is a summary of certain changes to the Fund since December 31, 2024. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after December 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective November 20, 2025, the Fund revised its principal investment policies to reflect that the Fund intends to be diversified in approximately the same proportion as the S&P 500 Index (the "Underlying Index") is diversified. The Fund may become “non‑diversified,” as defined in the Investment Company Act of 1940, as amended, solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by S&P Dow Jones Indices and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares S&P 500 Index Fund
Investor A Shares | BSPAX
Annual Shareholder Report — December 31, 2025
BSPAX-12/25-AR
iShares S&P 500 Index Fund
Investor P Shares | BSPPX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares S&P 500 Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the S&P 500 Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
This report describes changes to the Fund that occurred during the reporting period.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $38(a) | 0.35%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 17.45%.
- For the same period, the Fund’s benchmark, the S&P 500® Index returned 17.88%.
Domestic United States (“U.S.”) equities ended the first quarter in negative territory as the U.S. administration introduced broad shifts in global trade policy, including reciprocal tariffs that elevated economic uncertainty and pushed the S&P 500 briefly into correction territory. Markets remained highly sensitive to tariff announcements expected in April 2025. The Federal Open Market Committee (“FOMC”) held interest rates at 4.25%–4.50% in January and reaffirmed expectations for two rate cuts in 2025, though policymakers maintained a firmly data–dependent stance given persistent inflation and a still–resilient labor market.
U.S. equities rebounded in the second quarter and finished in positive territory as volatility eased following an early–April 2025 spike that drove the Chicago Board Options Exchange Volatility Index (“VIX”) to multi–year highs. Sentiment improved after the U.S. administration announced a 90–day pause on most proposed tariffs, temporarily alleviating trade pressures ahead of the July 2025 deadline. On April 9th, just after significant market volatility and rising economic concerns, President Trump and the White House suspended additional tariffs above a 10% base rate for most countries, with the pause set to expire in early July.
The FOMC kept rates unchanged at 4.25%–4.50% in both May and June, noting cautious progress toward the 2% inflation target. Strong corporate earnings and continued enthusiasm around artificial intelligence (“AI”) supported equity gains even as reciprocal tariffs on more than 60 countries, while additional trade deals were being agreed on, China tariffs were paused to allow for negotiations to continue. This added uncertainty to longer term economic forecasts.
U.S. equities continued to advance through the third quarter, supported by solid earnings momentum and receding market volatility. The FOMC maintained its data driven approach, holding rates steady in July 2025 and delivering the first rate cut of the year in September, lowering the target range to 4.00%–4.25%. The committee cited slowing job growth and a meaningful decline in hiring as key drivers of the “risk–management” cut, while tariff related inflation pressures remained a central consideration for future policy decisions. Despite mixed macroeconomic signals, investor sentiment remained broadly constructive.
Equity markets posted modest gains in the fourth quarter amid elevated volatility driven by concerns about an emerging AI bubble. Fears escalated throughout the quarter with investors worrying about lofty valuations and heavy capital expenditures, weighing on sentiment before stabilizing on signs of real revenue growth. The longest U.S. government shutdown in history, lasting 43 days, had a muted impact on markets, while renewed tariff negotiations with China in October 2025 added another layer of uncertainty. Labor conditions weakened as unemployment rose to 4.6% in November and inflation remained above the Federal Reserve’s 2% target, prompting the FOMC to cut rates by 25 bps in both October and December, ending the year with a 3.50%–3.75% target range and a continued commitment to data dependent policymaking heading into 2026.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 17.45 | % | 14.01 | % | 14.42 | % | |
| 11.29 | 12.79 | 13.80 | ||||
| 17.88 | 14.42 | 14.82 |
| Key Fund statistics | |
| $53,488,256,039 | |
| 1 | |
| $4,758,005 | |
| 14% |
Assuming maximum sales charges. Average annual total returns with and without sales charges reflect reductions for service fees.
Performance shown prior to the Investor P Shares inception date of August 6, 2018 is that of Class K Shares (which have no distribution or service fees) and was restated to reflect Investor P Shares fees.
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Material Fund changes
This is a summary of certain changes to the Fund since December 31, 2024. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after December 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective November 20, 2025, the Fund revised its principal investment policies to reflect that the Fund intends to be diversified in approximately the same proportion as the S&P 500 Index (the "Underlying Index") is diversified. The Fund may become “non‑diversified,” as defined in the Investment Company Act of 1940, as amended, solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by S&P Dow Jones Indices and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares S&P 500 Index Fund
Investor P Shares | BSPPX
Annual Shareholder Report — December 31, 2025
BSPPX-12/25-AR
iShares S&P 500 Index Fund
Class G Shares | BSPGX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares S&P 500 Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the S&P 500 Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
This report describes changes to the Fund that occurred during the reporting period.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $1(a) | 0.01%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Class G Shares returned 17.85%.
- For the same period, the Fund’s benchmark, the S&P 500® Index returned 17.88%.
Domestic United States (“U.S.”) equities ended the first quarter in negative territory as the U.S. administration introduced broad shifts in global trade policy, including reciprocal tariffs that elevated economic uncertainty and pushed the S&P 500 briefly into correction territory. Markets remained highly sensitive to tariff announcements expected in April 2025. The Federal Open Market Committee (“FOMC”) held interest rates at 4.25%–4.50% in January and reaffirmed expectations for two rate cuts in 2025, though policymakers maintained a firmly data–dependent stance given persistent inflation and a still–resilient labor market.
U.S. equities rebounded in the second quarter and finished in positive territory as volatility eased following an early–April 2025 spike that drove the Chicago Board Options Exchange Volatility Index (“VIX”) to multi–year highs. Sentiment improved after the U.S. administration announced a 90–day pause on most proposed tariffs, temporarily alleviating trade pressures ahead of the July 2025 deadline. On April 9th, just after significant market volatility and rising economic concerns, President Trump and the White House suspended additional tariffs above a 10% base rate for most countries, with the pause set to expire in early July.
The FOMC kept rates unchanged at 4.25%–4.50% in both May and June, noting cautious progress toward the 2% inflation target. Strong corporate earnings and continued enthusiasm around artificial intelligence (“AI”) supported equity gains even as reciprocal tariffs on more than 60 countries, while additional trade deals were being agreed on, China tariffs were paused to allow for negotiations to continue. This added uncertainty to longer term economic forecasts.
U.S. equities continued to advance through the third quarter, supported by solid earnings momentum and receding market volatility. The FOMC maintained its data driven approach, holding rates steady in July 2025 and delivering the first rate cut of the year in September, lowering the target range to 4.00%–4.25%. The committee cited slowing job growth and a meaningful decline in hiring as key drivers of the “risk–management” cut, while tariff related inflation pressures remained a central consideration for future policy decisions. Despite mixed macroeconomic signals, investor sentiment remained broadly constructive.
Equity markets posted modest gains in the fourth quarter amid elevated volatility driven by concerns about an emerging AI bubble. Fears escalated throughout the quarter with investors worrying about lofty valuations and heavy capital expenditures, weighing on sentiment before stabilizing on signs of real revenue growth. The longest U.S. government shutdown in history, lasting 43 days, had a muted impact on markets, while renewed tariff negotiations with China in October 2025 added another layer of uncertainty. Labor conditions weakened as unemployment rose to 4.6% in November and inflation remained above the Federal Reserve’s 2% target, prompting the FOMC to cut rates by 25 bps in both October and December, ending the year with a 3.50%–3.75% target range and a continued commitment to data dependent policymaking heading into 2026.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 17.85 | % | 14.40 | % | 14.80 | % | |
| 17.88 | 14.42 | 14.82 |
| Key Fund statistics | |
| $53,488,256,039 | |
| 1 | |
| $4,758,005 | |
| 14% |
Performance shown prior to the Class G Shares inception date of July 1, 2019 is that of Class K Shares (which have no distribution or service fees).
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Material Fund changes
This is a summary of certain changes to the Fund since December 31, 2024. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after December 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective November 20, 2025, the Fund revised its principal investment policies to reflect that the Fund intends to be diversified in approximately the same proportion as the S&P 500 Index (the "Underlying Index") is diversified. The Fund may become “non‑diversified,” as defined in the Investment Company Act of 1940, as amended, solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by S&P Dow Jones Indices and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares S&P 500 Index Fund
Class G Shares | BSPGX
Annual Shareholder Report — December 31, 2025
BSPGX-12/25-AR
iShares S&P 500 Index Fund
Class K Shares | WFSPX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares S&P 500 Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the S&P 500 Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
This report describes changes to the Fund that occurred during the reporting period.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $3(a) | 0.03%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 17.83%.
- For the same period, the Fund’s benchmark, the S&P 500® Index returned 17.88%.
Domestic United States (“U.S.”) equities ended the first quarter in negative territory as the U.S. administration introduced broad shifts in global trade policy, including reciprocal tariffs that elevated economic uncertainty and pushed the S&P 500 briefly into correction territory. Markets remained highly sensitive to tariff announcements expected in April 2025. The Federal Open Market Committee (“FOMC”) held interest rates at 4.25%–4.50% in January and reaffirmed expectations for two rate cuts in 2025, though policymakers maintained a firmly data–dependent stance given persistent inflation and a still–resilient labor market.
U.S. equities rebounded in the second quarter and finished in positive territory as volatility eased following an early–April 2025 spike that drove the Chicago Board Options Exchange Volatility Index (“VIX”) to multi–year highs. Sentiment improved after the U.S. administration announced a 90–day pause on most proposed tariffs, temporarily alleviating trade pressures ahead of the July 2025 deadline. On April 9th, just after significant market volatility and rising economic concerns, President Trump and the White House suspended additional tariffs above a 10% base rate for most countries, with the pause set to expire in early July.
The FOMC kept rates unchanged at 4.25%–4.50% in both May and June, noting cautious progress toward the 2% inflation target. Strong corporate earnings and continued enthusiasm around artificial intelligence (“AI”) supported equity gains even as reciprocal tariffs on more than 60 countries, while additional trade deals were being agreed on, China tariffs were paused to allow for negotiations to continue. This added uncertainty to longer term economic forecasts.
U.S. equities continued to advance through the third quarter, supported by solid earnings momentum and receding market volatility. The FOMC maintained its data driven approach, holding rates steady in July 2025 and delivering the first rate cut of the year in September, lowering the target range to 4.00%–4.25%. The committee cited slowing job growth and a meaningful decline in hiring as key drivers of the “risk–management” cut, while tariff related inflation pressures remained a central consideration for future policy decisions. Despite mixed macroeconomic signals, investor sentiment remained broadly constructive.
Equity markets posted modest gains in the fourth quarter amid elevated volatility driven by concerns about an emerging AI bubble. Fears escalated throughout the quarter with investors worrying about lofty valuations and heavy capital expenditures, weighing on sentiment before stabilizing on signs of real revenue growth. The longest U.S. government shutdown in history, lasting 43 days, had a muted impact on markets, while renewed tariff negotiations with China in October 2025 added another layer of uncertainty. Labor conditions weakened as unemployment rose to 4.6% in November and inflation remained above the Federal Reserve’s 2% target, prompting the FOMC to cut rates by 25 bps in both October and December, ending the year with a 3.50%–3.75% target range and a continued commitment to data dependent policymaking heading into 2026.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 17.83 | % | 14.38 | % | 14.79 | % | |
| 17.88 | 14.42 | 14.82 |
| Key Fund statistics | |
| $53,488,256,039 | |
| 1 | |
| $4,758,005 | |
| 14% |
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Material Fund changes
This is a summary of certain changes to the Fund since December 31, 2024. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after December 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective November 20, 2025, the Fund revised its principal investment policies to reflect that the Fund intends to be diversified in approximately the same proportion as the S&P 500 Index (the "Underlying Index") is diversified. The Fund may become “non‑diversified,” as defined in the Investment Company Act of 1940, as amended, solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Fund becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by S&P Dow Jones Indices and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares S&P 500 Index Fund
Class K Shares | WFSPX
Annual Shareholder Report — December 31, 2025
WFSPX-12/25-AR
Annual Shareholder Report — December 31, 2025
This report describes changes to the Fund that occurred during the reporting period.
What were the Master Portfolio costs for the last year ?
(based on a hypothetical $10,000 investment)
| Master Portfolio name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $ |
| Key Master Portfolio statistics | |
| $ | |
| $ | |
What did the Master Portfolio invest in?
(as of December 31, 2025)
| Sector allocation | ||
| Sector(a) | Percent of Net Assets |
|
| % | ||
| ( |
) | |
| Ten largest holdings | ||
| Security(b) | Percent of Net Assets |
|
| % | ||
| |
| |
| |
Material Master Portfolio changes
This is a summary of certain changes to the Master Portfolio since December 31, 2024.
Effective November 20, 2025 , the Master Portfolio revised its principal investment policies to reflect that the Master Portfolio intends to be diversified in approximately the same proportion as the S&P 500 Index (the "Underlying Index") is diversified. The Master Portfolio may become “non‑diversified,” as defined in the Investment Company Act of 1940, as amended, solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Master Portfolio becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index. Shareholder approval will not be sought if the Master Portfolio becomes “non‑diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Underlying Index.
Additional information
If you wish to view additional information about the Master Portfolio, including but not limited to financial statements and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
S&P 500 Index Master Portfolio
Annual Shareholder Report — December 31, 2025
12/25-AR
iShares U.S. Aggregate Bond Index Fund
Institutional Shares | BMOIX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares U.S. Aggregate Bond Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the U.S. Total Bond Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $10(a) | 0.10%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Institutional Shares returned 6.98%.
- For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index returned 7.30%.
What contributed to performance?
The U.S. investment-grade bond market produced a healthy total return in 2025, with modest price gains augmenting the contribution from yield. Inflation, while remaining above the U.S. Federal Reserve’s (Fed’s) target, nonetheless held near 3% for most of the year. The more benign inflation backdrop allowed the Fed to enact three quarter-point interest rate cuts and end its restrictive quantitative tightening policy. U.S. Treasuries produced gains in this environment, with the best returns occurring for the intermediate portion of the yield curve. Agency mortgage-backed securities also delivered positive returns, and corporate bonds outpaced government debt at a time of positive economic growth and hearty investor risk appetites.
What detracted from performance?
Reflecting the generally positive environment for the fixed-income market, no major segment of the index finished with a loss.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 6.98 | % | (0.46 | )% | 1.90 | % | |
| 7.30 | (0.36 | ) | 2.01 |
| Key Fund statistics | |
| $3,758,976,185 | |
| 1 | |
| $1,219,059 | |
| 93% |
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by Bloomberg Index Services Limited and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares U.S. Aggregate Bond Index Fund
Institutional Shares | BMOIX
Annual Shareholder Report — December 31, 2025
BMOIX-12/25-AR
iShares U.S. Aggregate Bond Index Fund
Investor A Shares | BMOAX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares U.S. Aggregate Bond Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the U.S. Total Bond Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $36(a) | 0.35%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Investor A Shares returned 6.71%.
- For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index returned 7.30%.
What contributed to performance?
The U.S. investment-grade bond market produced a healthy total return in 2025, with modest price gains augmenting the contribution from yield. Inflation, while remaining above the U.S. Federal Reserve’s (Fed’s) target, nonetheless held near 3% for most of the year. The more benign inflation backdrop allowed the Fed to enact three quarter-point interest rate cuts and end its restrictive quantitative tightening policy. U.S. Treasuries produced gains in this environment, with the best returns occurring for the intermediate portion of the yield curve. Agency mortgage-backed securities also delivered positive returns, and corporate bonds outpaced government debt at a time of positive economic growth and hearty investor risk appetites.
What detracted from performance?
Reflecting the generally positive environment for the fixed-income market, no major segment of the index finished with a loss.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 6.71 | % | (0.71 | )% | 1.65 | % | |
| 7.30 | (0.36 | ) | 2.01 |
| Key Fund statistics | |
| $3,758,976,185 | |
| 1 | |
| $1,219,059 | |
| 93% |
Average annual total returns reflect reductions for service fees.
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by Bloomberg Index Services Limited and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares U.S. Aggregate Bond Index Fund
Investor A Shares | BMOAX
Annual Shareholder Report — December 31, 2025
BMOAX-12/25-AR
iShares U.S. Aggregate Bond Index Fund
Investor P Shares | BMOPX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares U.S. Aggregate Bond Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the U.S. Total Bond Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $36(a) | 0.35%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Investor P Shares returned 6.83%.
- For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index returned 7.30%.
What contributed to performance?
The U.S. investment-grade bond market produced a healthy total return in 2025, with modest price gains augmenting the contribution from yield. Inflation, while remaining above the U.S. Federal Reserve’s (Fed’s) target, nonetheless held near 3% for most of the year. The more benign inflation backdrop allowed the Fed to enact three quarter-point interest rate cuts and end its restrictive quantitative tightening policy. U.S. Treasuries produced gains in this environment, with the best returns occurring for the intermediate portion of the yield curve. Agency mortgage-backed securities also delivered positive returns, and corporate bonds outpaced government debt at a time of positive economic growth and hearty investor risk appetites.
What detracted from performance?
Reflecting the generally positive environment for the fixed-income market, no major segment of the index finished with a loss.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 6.83 | % | (0.71 | )% | 1.65 | % | |
| 2.55 | (1.52 | ) | 1.23 | |||
| 7.30 | (0.36 | ) | 2.01 |
| Key Fund statistics | |
| $3,758,976,185 | |
| 1 | |
| $1,219,059 | |
| 93% |
Assuming maximum sales charges. Average annual total returns with and without sales charges reflect reductions for service fees.
Performance shown prior to the Investor P Shares inception date of August 6, 2018 is that of Class K Shares (which have no distribution or service fees) and was restated to reflect Investor P Shares fees.
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by Bloomberg Index Services Limited and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares U.S. Aggregate Bond Index Fund
Investor P Shares | BMOPX
Annual Shareholder Report — December 31, 2025
BMOPX-12/25-AR
iShares U.S. Aggregate Bond Index Fund
Class K Shares | WFBIX
Annual Shareholder Report — December 31, 2025
This annual shareholder report contains important information about iShares U.S. Aggregate Bond Index Fund (the “Fund”) for the period of January 1, 2025 to December 31, 2025. The Fund invests all of its assets in the U.S. Total Bond Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio. You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.
What were the Fund costs for the last year ?
(based on a hypothetical $10,000 investment)
| Class name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $5(a) | 0.05%(a) |
| Because the Fund invests all of its assets in the Master Portfolio, the expense example reflects the net expenses of both the Fund and the Master Portfolio. |
How did the Fund perform last year ?
- For the reporting period ended December 31, 2025, the Fund’s Class K Shares returned 7.15%.
- For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index returned 7.30%.
What contributed to performance?
The U.S. investment-grade bond market produced a healthy total return in 2025, with modest price gains augmenting the contribution from yield. Inflation, while remaining above the U.S. Federal Reserve’s (Fed’s) target, nonetheless held near 3% for most of the year. The more benign inflation backdrop allowed the Fed to enact three quarter-point interest rate cuts and end its restrictive quantitative tightening policy. U.S. Treasuries produced gains in this environment, with the best returns occurring for the intermediate portion of the yield curve. Agency mortgage-backed securities also delivered positive returns, and corporate bonds outpaced government debt at a time of positive economic growth and hearty investor risk appetites.
What detracted from performance?
Reflecting the generally positive environment for the fixed-income market, no major segment of the index finished with a loss.
The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.
Fund performance
Cumulative performance: January 1, 2016 through December 31, 2025
Initial investment of $10,000
See “Average annual total returns” for additional information on fund performance.
| Average annual total returns | ||||||
| 1 Year | 5 Years | 10 Years | ||||
| 7.15 | % | (0.41 | )% | 1.96 | % | |
| 7.30 | (0.36 | ) | 2.01 |
| Key Fund statistics | |
| $3,758,976,185 | |
| 1 | |
| $1,219,059 | |
| 93% |
Past performance is not an indication of future results. Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. Visit blackrock.com for more recent performance information.
Additional information
If you wish to view additional information about the Fund, including but not limited to financial statements, the Fund’s prospectus, and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
Householding
The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.
The Fund is not sponsored, endorsed, issued, sold, or promoted by Bloomberg Index Services Limited and its affiliates, nor does this company make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the company listed above.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
iShares U.S. Aggregate Bond Index Fund
Class K Shares | WFBIX
Annual Shareholder Report — December 31, 2025
WFBIX-12/25-AR
Annual Shareholder Report — December 31, 2025
What were the Master Portfolio costs for the last year ?
(based on a hypothetical $10,000 investment)
| Master Portfolio name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $ |
| Key Master Portfolio statistics | |
| $ | |
| $ | |
What did the Master Portfolio invest in?
(as of December 31, 2025)
| Portfolio composition | ||
| Investment Type | Percent of Total Investments(a) |
|
| % | ||
| Credit quality allocation | ||
| Credit Rating(b) | Percent of Total Investments(a) |
|
| % | ||
| |
| |
| |
Additional information
If you wish to view additional information about the Master Portfolio, including but not limited to financial statements and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
U.S. Total Bond Index Master Portfolio
Annual Shareholder Report — December 31, 2025
12/25-AR
Annual Shareholder Report — December 31, 2025
What were the Master Portfolio costs for the last year ?
(based on a hypothetical $10,000 investment)
| Master Portfolio name | Costs of a $10,000 investment |
Costs paid as a percentage of a $10,000 investment |
| $ |
| Key Master Portfolio statistics | |
| $ | |
| $ | |
What did the Master Portfolio invest in?
(as of December 31, 2025)
| Geographic allocation | ||
| Country/Geographic Region | Percent of Net Assets |
|
| % | ||
| ( |
) | |
| Ten largest holdings | ||
| Security(a) | Percent of Net Assets |
|
| % | ||
| |
| |
Additional information
If you wish to view additional information about the Master Portfolio, including but not limited to financial statements and proxy voting policies and procedures, please visit blackrock.com/fundreports. For proxy voting records, visit blackrock.com/proxyrecords.
©2025 BlackRock, Inc. or its affiliates. All rights reserved. BLACKROCK is a registered trademark of BlackRock, Inc. or its affiliates. All other trademarks are those of their respective owners.
International Tilts Master Portfolio
Annual Shareholder Report — December 31, 2025
12/25-AR
