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 |
|---|---|---|
Institutional Shares | $ |
How did the Fund perform last year?
For the reporting period ended July 31, 2025, the Fund's Institutional Shares returned 4.77%.
For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index, returned 3.38% and the ICE BofA 6-Month U.S. Treasury Bill Index, returned 4.60%.
What contributed to performance?
The Fund’s duration positioning contributed to absolute performance (duration is a measure of interest rate sensitivity). Asset allocation—namely, positions in U.S. Treasuries, commercial paper, and investment-grade corporate bonds—also helped results. The Fund’s cash position had no material impact on performance.
What detracted from performance?
At a time of positive returns for the broader fixed-income markets, no aspect of the Fund’s positioning was a significant detractor.
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: August 1, 2015 through July 31, 2025
Initial Investment of $10,000
Institutional Shares | Bloomberg U.S. Aggregate Bond Index | ICE BofA 6-Month U.S. Treasury Bill Index | |
|---|---|---|---|
Aug 15 | $ | $ | $ |
Sep 15 | $ | $ | $ |
Oct 15 | $ | $ | $ |
Nov 15 | $ | $ | $ |
Dec 15 | $ | $ | $ |
Jan 16 | $ | $ | $ |
Feb 16 | $ | $ | $ |
Mar 16 | $ | $ | $ |
Apr 16 | $ | $ | $ |
May 16 | $ | $ | $ |
Jun 16 | $ | $ | $ |
Jul 16 | $ | $ | $ |
Aug 16 | $ | $ | $ |
Sep 16 | $ | $ | $ |
Oct 16 | $ | $ | $ |
Nov 16 | $ | $ | $ |
Dec 16 | $ | $ | $ |
Jan 17 | $ | $ | $ |
Feb 17 | $ | $ | $ |
Mar 17 | $ | $ | $ |
Apr 17 | $ | $ | $ |
May 17 | $ | $ | $ |
Jun 17 | $ | $ | $ |
Jul 17 | $ | $ | $ |
Aug 17 | $ | $ | $ |
Sep 17 | $ | $ | $ |
Oct 17 | $ | $ | $ |
Nov 17 | $ | $ | $ |
Dec 17 | $ | $ | $ |
Jan 18 | $ | $ | $ |
Feb 18 | $ | $ | $ |
Mar 18 | $ | $ | $ |
Apr 18 | $ | $ | $ |
May 18 | $ | $ | $ |
Jun 18 | $ | $ | $ |
Jul 18 | $ | $ | $ |
Aug 18 | $ | $ | $ |
Sep 18 | $ | $ | $ |
Oct 18 | $ | $ | $ |
Nov 18 | $ | $ | $ |
Dec 18 | $ | $ | $ |
Jan 19 | $ | $ | $ |
Feb 19 | $ | $ | $ |
Mar 19 | $ | $ | $ |
Apr 19 | $ | $ | $ |
May 19 | $ | $ | $ |
Jun 19 | $ | $ | $ |
Jul 19 | $ | $ | $ |
Aug 19 | $ | $ | $ |
Sep 19 | $ | $ | $ |
Oct 19 | $ | $ | $ |
Nov 19 | $ | $ | $ |
Dec 19 | $ | $ | $ |
Jan 20 | $ | $ | $ |
Feb 20 | $ | $ | $ |
Mar 20 | $ | $ | $ |
Apr 20 | $ | $ | $ |
May 20 | $ | $ | $ |
Jun 20 | $ | $ | $ |
Jul 20 | $ | $ | $ |
Aug 20 | $ | $ | $ |
Sep 20 | $ | $ | $ |
Oct 20 | $ | $ | $ |
Nov 20 | $ | $ | $ |
Dec 20 | $ | $ | $ |
Jan 21 | $ | $ | $ |
Feb 21 | $ | $ | $ |
Mar 21 | $ | $ | $ |
Apr 21 | $ | $ | $ |
May 21 | $ | $ | $ |
Jun 21 | $ | $ | $ |
Jul 21 | $ | $ | $ |
Aug 21 | $ | $ | $ |
Sep 21 | $ | $ | $ |
Oct 21 | $ | $ | $ |
Nov 21 | $ | $ | $ |
Dec 21 | $ | $ | $ |
Jan 22 | $ | $ | $ |
Feb 22 | $ | $ | $ |
Mar 22 | $ | $ | $ |
Apr 22 | $ | $ | $ |
May 22 | $ | $ | $ |
Jun 22 | $ | $ | $ |
Jul 22 | $ | $ | $ |
Aug 22 | $ | $ | $ |
Sep 22 | $ | $ | $ |
Oct 22 | $ | $ | $ |
Nov 22 | $ | $ | $ |
Dec 22 | $ | $ | $ |
Jan 23 | $ | $ | $ |
Feb 23 | $ | $ | $ |
Mar 23 | $ | $ | $ |
Apr 23 | $ | $ | $ |
May 23 | $ | $ | $ |
Jun 23 | $ | $ | $ |
Jul 23 | $ | $ | $ |
Aug 23 | $ | $ | $ |
Sep 23 | $ | $ | $ |
Oct 23 | $ | $ | $ |
Nov 23 | $ | $ | $ |
Dec 23 | $ | $ | $ |
Jan 24 | $ | $ | $ |
Feb 24 | $ | $ | $ |
Mar 24 | $ | $ | $ |
Apr 24 | $ | $ | $ |
May 24 | $ | $ | $ |
Jun 24 | $ | $ | $ |
Jul 24 | $ | $ | $ |
Aug 24 | $ | $ | $ |
Sep 24 | $ | $ | $ |
Oct 24 | $ | $ | $ |
Nov 24 | $ | $ | $ |
Dec 24 | $ | $ | $ |
Jan 25 | $ | $ | $ |
Feb 25 | $ | $ | $ |
Mar 25 | $ | $ | $ |
Apr 25 | $ | $ | $ |
May 25 | $ | $ | $ |
Jun 25 | $ | $ | $ |
Jul 25 | $ | $ | $ |
See “Average annual total returns” for additional information on fund performance.
Average annual total returns
Average Annual Total Returns | 1 Year | 5 Years | 10 Years |
|---|---|---|---|
Institutional Shares ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |||
Bloomberg U.S. Aggregate Bond Index........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | ( | ||
Key Fund statistics
Net Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | $ |
|---|---|
Number of Portfolio Holdings........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Net Investment Advisory Fees........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | $ |
Portfolio Turnover Rate........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ |
On December 1, 2023, the Fund began to compare its performance to the standard pricing time of the ICE BofA 6-Month U.S. Treasury Bill Index (the “Index”). Index data prior to March 1, 2021 is for the Index’s standard pricing time of 3pm. Index data from March 1, 2021 through November 30, 2023 is for a custom 4pm pricing variant of the Index. Index returns beginning on December 1, 2023 reflect the Index’s new standard pricing time of 4pm. The change of the Index’s standard pricing time from 3pm to 4pm resulted in the discontinuation of the custom 4pm pricing variant used from March 1, 2021 through November 30, 2023.
What did the Fund invest in?
(as of July 31, 2025)
Portfolio composition
Maturity allocation
Asset Type | Percent of
Net Assets |
|---|---|
Corporate Bonds........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
U.S. Treasury Obligations........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Asset-Backed Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Foreign Agency Obligations........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Municipal Bonds........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Short-Term Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Liabilities in Excess of Other Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | ( |
Percent of
Net Assets | |
|---|---|
1-7 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
8-14 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
15-30 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
31-60 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
61-90 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
91-120 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
121-150 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
>150 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ |
Material fund changes
This is a summary of certain changes to the Fund since July 31, 2024. For more complete information, you may review the Fund's next prospectus, which we expect to be available approximately 120 days after July 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective July 23, 2025, the Fund adopted a strategy, under normal market conditions, to invest in U.S. dollar-denominated investment grade and short-term fixed and floating rate debt securities maturing in three years or less (with certain exceptions) and to maintain an average duration of half a year or less.
Prior to July 23, 2025, the Fund had a strategy, under normal market conditions, to invest in U.S. dollar-denominated investment grade and short-term fixed and floating rate debt securities maturing in three years or less (with certain exceptions) and to maintain a dollar-weighted average maturity of 180 days or less and a dollar-weighted average life of 365 days or less.
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, ICE Data Indices, LLC, and their respective affiliates, nor do these companies make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the companies 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.
BISOX-07/25-AR
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 |
|---|---|---|
Investor A Shares | $ |
How did the Fund perform last year?
For the reporting period ended July 31, 2025, the Fund's Investor A Shares returned 4.65%.
For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index, returned 3.38% and the ICE BofA 6-Month U.S. Treasury Bill Index, returned 4.60%.
What contributed to performance?
The Fund’s duration positioning contributed to absolute performance (duration is a measure of interest rate sensitivity). Asset allocation—namely, positions in U.S. Treasuries, commercial paper, and investment-grade corporate bonds—also helped results. The Fund’s cash position had no material impact on performance.
What detracted from performance?
At a time of positive returns for the broader fixed-income markets, no aspect of the Fund’s positioning was a significant detractor.
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: August 1, 2015 through July 31, 2025
Initial Investment of $10,000
Investor A Shares | Bloomberg U.S. Aggregate Bond Index | ICE BofA 6-Month U.S. Treasury Bill Index | |
|---|---|---|---|
Aug 15 | $ | $ | $ |
Sep 15 | $ | $ | $ |
Oct 15 | $ | $ | $ |
Nov 15 | $ | $ | $ |
Dec 15 | $ | $ | $ |
Jan 16 | $ | $ | $ |
Feb 16 | $ | $ | $ |
Mar 16 | $ | $ | $ |
Apr 16 | $ | $ | $ |
May 16 | $ | $ | $ |
Jun 16 | $ | $ | $ |
Jul 16 | $ | $ | $ |
Aug 16 | $ | $ | $ |
Sep 16 | $ | $ | $ |
Oct 16 | $ | $ | $ |
Nov 16 | $ | $ | $ |
Dec 16 | $ | $ | $ |
Jan 17 | $ | $ | $ |
Feb 17 | $ | $ | $ |
Mar 17 | $ | $ | $ |
Apr 17 | $ | $ | $ |
May 17 | $ | $ | $ |
Jun 17 | $ | $ | $ |
Jul 17 | $ | $ | $ |
Aug 17 | $ | $ | $ |
Sep 17 | $ | $ | $ |
Oct 17 | $ | $ | $ |
Nov 17 | $ | $ | $ |
Dec 17 | $ | $ | $ |
Jan 18 | $ | $ | $ |
Feb 18 | $ | $ | $ |
Mar 18 | $ | $ | $ |
Apr 18 | $ | $ | $ |
May 18 | $ | $ | $ |
Jun 18 | $ | $ | $ |
Jul 18 | $ | $ | $ |
Aug 18 | $ | $ | $ |
Sep 18 | $ | $ | $ |
Oct 18 | $ | $ | $ |
Nov 18 | $ | $ | $ |
Dec 18 | $ | $ | $ |
Jan 19 | $ | $ | $ |
Feb 19 | $ | $ | $ |
Mar 19 | $ | $ | $ |
Apr 19 | $ | $ | $ |
May 19 | $ | $ | $ |
Jun 19 | $ | $ | $ |
Jul 19 | $ | $ | $ |
Aug 19 | $ | $ | $ |
Sep 19 | $ | $ | $ |
Oct 19 | $ | $ | $ |
Nov 19 | $ | $ | $ |
Dec 19 | $ | $ | $ |
Jan 20 | $ | $ | $ |
Feb 20 | $ | $ | $ |
Mar 20 | $ | $ | $ |
Apr 20 | $ | $ | $ |
May 20 | $ | $ | $ |
Jun 20 | $ | $ | $ |
Jul 20 | $ | $ | $ |
Aug 20 | $ | $ | $ |
Sep 20 | $ | $ | $ |
Oct 20 | $ | $ | $ |
Nov 20 | $ | $ | $ |
Dec 20 | $ | $ | $ |
Jan 21 | $ | $ | $ |
Feb 21 | $ | $ | $ |
Mar 21 | $ | $ | $ |
Apr 21 | $ | $ | $ |
May 21 | $ | $ | $ |
Jun 21 | $ | $ | $ |
Jul 21 | $ | $ | $ |
Aug 21 | $ | $ | $ |
Sep 21 | $ | $ | $ |
Oct 21 | $ | $ | $ |
Nov 21 | $ | $ | $ |
Dec 21 | $ | $ | $ |
Jan 22 | $ | $ | $ |
Feb 22 | $ | $ | $ |
Mar 22 | $ | $ | $ |
Apr 22 | $ | $ | $ |
May 22 | $ | $ | $ |
Jun 22 | $ | $ | $ |
Jul 22 | $ | $ | $ |
Aug 22 | $ | $ | $ |
Sep 22 | $ | $ | $ |
Oct 22 | $ | $ | $ |
Nov 22 | $ | $ | $ |
Dec 22 | $ | $ | $ |
Jan 23 | $ | $ | $ |
Feb 23 | $ | $ | $ |
Mar 23 | $ | $ | $ |
Apr 23 | $ | $ | $ |
May 23 | $ | $ | $ |
Jun 23 | $ | $ | $ |
Jul 23 | $ | $ | $ |
Aug 23 | $ | $ | $ |
Sep 23 | $ | $ | $ |
Oct 23 | $ | $ | $ |
Nov 23 | $ | $ | $ |
Dec 23 | $ | $ | $ |
Jan 24 | $ | $ | $ |
Feb 24 | $ | $ | $ |
Mar 24 | $ | $ | $ |
Apr 24 | $ | $ | $ |
May 24 | $ | $ | $ |
Jun 24 | $ | $ | $ |
Jul 24 | $ | $ | $ |
Aug 24 | $ | $ | $ |
Sep 24 | $ | $ | $ |
Oct 24 | $ | $ | $ |
Nov 24 | $ | $ | $ |
Dec 24 | $ | $ | $ |
Jan 25 | $ | $ | $ |
Feb 25 | $ | $ | $ |
Mar 25 | $ | $ | $ |
Apr 25 | $ | $ | $ |
May 25 | $ | $ | $ |
Jun 25 | $ | $ | $ |
Jul 25 | $ | $ | $ |
See “Average annual total returns” for additional information on fund performance.
Average annual total returns
Average Annual Total Returns | 1 Year | 5 Years | 10 Years |
|---|---|---|---|
Investor A Shares ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |||
Bloomberg U.S. Aggregate Bond Index........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | ( | ||
Key Fund statistics
Net Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | $ |
|---|---|
Number of Portfolio Holdings........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Net Investment Advisory Fees........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | $ |
Portfolio Turnover Rate........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ |
Average annual total returns reflect reductions for service fees.
Performance shown prior to the Investor A Shares inception date of March 9, 2018 is that of Class K Shares (which have no distribution or service fees) and was restated to reflect Investor A Shares fees.
On December 1, 2023, the Fund began to compare its performance to the standard pricing time of the ICE BofA 6-Month U.S. Treasury Bill Index (the “Index”). Index data prior to March 1, 2021 is for the Index’s standard pricing time of 3pm. Index data from March 1, 2021 through November 30, 2023 is for a custom 4pm pricing variant of the Index. Index returns beginning on December 1, 2023 reflect the Index’s new standard pricing time of 4pm. The change of the Index’s standard pricing time from 3pm to 4pm resulted in the discontinuation of the custom 4pm pricing variant used from March 1, 2021 through November 30, 2023.
What did the Fund invest in?
(as of July 31, 2025)
Portfolio composition
Maturity allocation
Asset Type | Percent of
Net Assets |
|---|---|
Corporate Bonds........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
U.S. Treasury Obligations........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Asset-Backed Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Foreign Agency Obligations........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Municipal Bonds........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Short-Term Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Liabilities in Excess of Other Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | ( |
Percent of
Net Assets | |
|---|---|
1-7 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
8-14 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
15-30 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
31-60 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
61-90 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
91-120 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
121-150 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
>150 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ |
Material fund changes
This is a summary of certain changes to the Fund since July 31, 2024. For more complete information, you may review the Fund's next prospectus, which we expect to be available approximately 120 days after July 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective July 23, 2025, the Fund adopted a strategy, under normal market conditions, to invest in U.S. dollar-denominated investment grade and short-term fixed and floating rate debt securities maturing in three years or less (with certain exceptions) and to maintain an average duration of half a year or less.
Prior to July 23, 2025, the Fund had a strategy, under normal market conditions, to invest in U.S. dollar-denominated investment grade and short-term fixed and floating rate debt securities maturing in three years or less (with certain exceptions) and to maintain a dollar-weighted average maturity of 180 days or less and a dollar-weighted average life of 365 days or less.
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, ICE Data Indices, LLC, and their respective affiliates, nor do these companies make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the companies 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.
BASOX-07/25-AR
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 |
|---|---|---|
Class K Shares | $ |
How did the Fund perform last year?
For the reporting period ended July 31, 2025, the Fund's Class K Shares returned 4.76%.
For the same period, the Fund’s benchmark, the Bloomberg U.S. Aggregate Bond Index, returned 3.38% and the ICE BofA 6-Month U.S. Treasury Bill Index, returned 4.60%.
What contributed to performance?
The Fund’s duration positioning contributed to absolute performance (duration is a measure of interest rate sensitivity). Asset allocation—namely, positions in U.S. Treasuries, commercial paper, and investment-grade corporate bonds—also helped results. The Fund’s cash position had no material impact on performance.
What detracted from performance?
At a time of positive returns for the broader fixed-income markets, no aspect of the Fund’s positioning was a significant detractor.
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: August 1, 2015 through July 31, 2025
Initial Investment of $10,000
Class K Shares | Bloomberg U.S. Aggregate Bond Index | ICE BofA 6-Month U.S. Treasury Bill Index | |
|---|---|---|---|
Aug 15 | $ | $ | $ |
Sep 15 | $ | $ | $ |
Oct 15 | $ | $ | $ |
Nov 15 | $ | $ | $ |
Dec 15 | $ | $ | $ |
Jan 16 | $ | $ | $ |
Feb 16 | $ | $ | $ |
Mar 16 | $ | $ | $ |
Apr 16 | $ | $ | $ |
May 16 | $ | $ | $ |
Jun 16 | $ | $ | $ |
Jul 16 | $ | $ | $ |
Aug 16 | $ | $ | $ |
Sep 16 | $ | $ | $ |
Oct 16 | $ | $ | $ |
Nov 16 | $ | $ | $ |
Dec 16 | $ | $ | $ |
Jan 17 | $ | $ | $ |
Feb 17 | $ | $ | $ |
Mar 17 | $ | $ | $ |
Apr 17 | $ | $ | $ |
May 17 | $ | $ | $ |
Jun 17 | $ | $ | $ |
Jul 17 | $ | $ | $ |
Aug 17 | $ | $ | $ |
Sep 17 | $ | $ | $ |
Oct 17 | $ | $ | $ |
Nov 17 | $ | $ | $ |
Dec 17 | $ | $ | $ |
Jan 18 | $ | $ | $ |
Feb 18 | $ | $ | $ |
Mar 18 | $ | $ | $ |
Apr 18 | $ | $ | $ |
May 18 | $ | $ | $ |
Jun 18 | $ | $ | $ |
Jul 18 | $ | $ | $ |
Aug 18 | $ | $ | $ |
Sep 18 | $ | $ | $ |
Oct 18 | $ | $ | $ |
Nov 18 | $ | $ | $ |
Dec 18 | $ | $ | $ |
Jan 19 | $ | $ | $ |
Feb 19 | $ | $ | $ |
Mar 19 | $ | $ | $ |
Apr 19 | $ | $ | $ |
May 19 | $ | $ | $ |
Jun 19 | $ | $ | $ |
Jul 19 | $ | $ | $ |
Aug 19 | $ | $ | $ |
Sep 19 | $ | $ | $ |
Oct 19 | $ | $ | $ |
Nov 19 | $ | $ | $ |
Dec 19 | $ | $ | $ |
Jan 20 | $ | $ | $ |
Feb 20 | $ | $ | $ |
Mar 20 | $ | $ | $ |
Apr 20 | $ | $ | $ |
May 20 | $ | $ | $ |
Jun 20 | $ | $ | $ |
Jul 20 | $ | $ | $ |
Aug 20 | $ | $ | $ |
Sep 20 | $ | $ | $ |
Oct 20 | $ | $ | $ |
Nov 20 | $ | $ | $ |
Dec 20 | $ | $ | $ |
Jan 21 | $ | $ | $ |
Feb 21 | $ | $ | $ |
Mar 21 | $ | $ | $ |
Apr 21 | $ | $ | $ |
May 21 | $ | $ | $ |
Jun 21 | $ | $ | $ |
Jul 21 | $ | $ | $ |
Aug 21 | $ | $ | $ |
Sep 21 | $ | $ | $ |
Oct 21 | $ | $ | $ |
Nov 21 | $ | $ | $ |
Dec 21 | $ | $ | $ |
Jan 22 | $ | $ | $ |
Feb 22 | $ | $ | $ |
Mar 22 | $ | $ | $ |
Apr 22 | $ | $ | $ |
May 22 | $ | $ | $ |
Jun 22 | $ | $ | $ |
Jul 22 | $ | $ | $ |
Aug 22 | $ | $ | $ |
Sep 22 | $ | $ | $ |
Oct 22 | $ | $ | $ |
Nov 22 | $ | $ | $ |
Dec 22 | $ | $ | $ |
Jan 23 | $ | $ | $ |
Feb 23 | $ | $ | $ |
Mar 23 | $ | $ | $ |
Apr 23 | $ | $ | $ |
May 23 | $ | $ | $ |
Jun 23 | $ | $ | $ |
Jul 23 | $ | $ | $ |
Aug 23 | $ | $ | $ |
Sep 23 | $ | $ | $ |
Oct 23 | $ | $ | $ |
Nov 23 | $ | $ | $ |
Dec 23 | $ | $ | $ |
Jan 24 | $ | $ | $ |
Feb 24 | $ | $ | $ |
Mar 24 | $ | $ | $ |
Apr 24 | $ | $ | $ |
May 24 | $ | $ | $ |
Jun 24 | $ | $ | $ |
Jul 24 | $ | $ | $ |
Aug 24 | $ | $ | $ |
Sep 24 | $ | $ | $ |
Oct 24 | $ | $ | $ |
Nov 24 | $ | $ | $ |
Dec 24 | $ | $ | $ |
Jan 25 | $ | $ | $ |
Feb 25 | $ | $ | $ |
Mar 25 | $ | $ | $ |
Apr 25 | $ | $ | $ |
May 25 | $ | $ | $ |
Jun 25 | $ | $ | $ |
Jul 25 | $ | $ | $ |
See “Average annual total returns” for additional information on fund performance.
Average annual total returns
Average Annual Total Returns | 1 Year | 5 Years | 10 Years |
|---|---|---|---|
Class K Shares ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |||
Bloomberg U.S. Aggregate Bond Index........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | ( | ||
Key Fund statistics
Net Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | $ |
|---|---|
Number of Portfolio Holdings........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Net Investment Advisory Fees........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | $ |
Portfolio Turnover Rate........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ |
On December 1, 2023, the Fund began to compare its performance to the standard pricing time of the ICE BofA 6-Month U.S. Treasury Bill Index (the “Index”). Index data prior to March 1, 2021 is for the Index’s standard pricing time of 3pm. Index data from March 1, 2021 through November 30, 2023 is for a custom 4pm pricing variant of the Index. Index returns beginning on December 1, 2023 reflect the Index’s new standard pricing time of 4pm. The change of the Index’s standard pricing time from 3pm to 4pm resulted in the discontinuation of the custom 4pm pricing variant used from March 1, 2021 through November 30, 2023.
What did the Fund invest in?
(as of July 31, 2025)
Portfolio composition
Maturity allocation
Asset Type | Percent of
Net Assets |
|---|---|
Corporate Bonds........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
U.S. Treasury Obligations........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Asset-Backed Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Foreign Agency Obligations........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Municipal Bonds........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Short-Term Securities........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
Liabilities in Excess of Other Assets........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | ( |
Percent of
Net Assets | |
|---|---|
1-7 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
8-14 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
15-30 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
31-60 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
61-90 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
91-120 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
121-150 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ | |
>150 days........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ |
Material fund changes
This is a summary of certain changes to the Fund since July 31, 2024. For more complete information, you may review the Fund's next prospectus, which we expect to be available approximately 120 days after July 31, 2025 at blackrock.com/fundreports or upon request by contacting us at (800) 441-7762.
Effective July 23, 2025, the Fund adopted a strategy, under normal market conditions, to invest in U.S. dollar-denominated investment grade and short-term fixed and floating rate debt securities maturing in three years or less (with certain exceptions) and to maintain an average duration of half a year or less.
Prior to July 23, 2025, the Fund had a strategy, under normal market conditions, to invest in U.S. dollar-denominated investment grade and short-term fixed and floating rate debt securities maturing in three years or less (with certain exceptions) and to maintain a dollar-weighted average maturity of 180 days or less and a dollar-weighted average life of 365 days or less.
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, ICE Data Indices, LLC, and their respective affiliates, nor do these companies make any representation regarding the advisability of investing in the Fund. BlackRock is not affiliated with the companies 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.
BBSOX-07/25-AR