SP 930 Vanguard Extended Duration Treasury ETF

December 19, 2025 (as supplemented on June 30, 2026)

Summary Prospectus

Vanguard Extended Duration Treasury ETF

Exchange-traded fund shares that are not individually redeemable and are listed on NYSE Arca

Vanguard Extended Duration Treasury Index Fund ETF Shares (EDV)

The Fund’s statutory Prospectus and Statement of Additional Information dated December 19, 2025 (as supplemented on June 30, 2026), as may be amended or supplemented, are incorporated into and made part of this Summary Prospectus by reference.

Before you invest, you may want to review the Fund’s Prospectus, which contains more information about the Fund and its risks. You can find the Fund’s Prospectus and other information about the Fund online at www.vanguard.com/prospectus and http://personal.vanguard.com/us/literature/reports/ETFs. You can also obtain this information at no cost by calling 866-499-8473 or by sending an email request to online@vanguard.com.

The Securities and Exchange Commission (SEC) has not approved or disapproved these securities or passed upon the adequacy of this Prospectus. Any representation to the contrary is a criminal offense.

Investment Objective

Vanguard Extended Duration Treasury ETF, an exchange-traded share class of Vanguard Extended Duration Treasury Index Fund (the “Fund”), seeks to track the performance of an index of extended-duration zero-coupon U.S. Treasury securities.

Fees and Expenses

The following tables describe the fees and expenses you may pay if you buy, hold, and sell ETF Shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.

Shareholder Fees
(Fees paid directly from your investment)


Transaction Fee on Purchases and Sales	None*
Transaction Fee on Reinvested Dividends	None*
Transaction Fee on Conversion to ETF Shares	None*

None through Vanguard (Broker fees vary)

Annual Fund Operating Expenses
(Expenses that you pay each year as a percentage of the value of your investment)


Management Fees	0.04 %
12b-1 Distribution Fee	None
Other Expenses	0.01 %
Total Annual Fund Operating Expenses	0.05 %

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

1 Year	3 Years	5 Years	10 Years
$5	$16	$28	$64

This example does not include the brokerage commissions that you may pay to buy and sell ETF Shares of the Fund.

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 15% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the Bloomberg U.S. Treasury STRIPS 20–30 Year Equal Par Bond Index (the “Target Index”), which includes zero-coupon U.S. Treasury securities (“Treasury STRIPS”) with maturities ranging from 20 to 30 years. Treasury STRIPS are backed by the full faith and credit of the U.S. government and represent a single coupon (principal) payment from a U.S. Treasury security that has been “stripped” into separately tradable components. Treasury STRIPS are referred to as “zero-coupon” because they do not pay interest—the only time an investor receives payment for a Treasury STRIP is at its maturity. Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in the U.S. Treasury securities that make up the Target Index. The Fund invests by sampling the Target Index, meaning that it holds a range of securities that, in the aggregate, approximates the full Target Index in terms of key risk factors and other characteristics.

Duration is a measure of the price sensitivity of a bond or a bond fund to changes in interest rates. For example, if a bond has a duration of two years, its price would fall by approximately 2% when interest rates rise by 1%. On the other hand, the bond’s price would rise by approximately 2% when interest rates fall by 1%. The Fund seeks to maintain a dollar-weighted average duration with that of the Target Index, which was 23.8 years as of August 31, 2025. The Fund also seeks to maintain a dollar-weighted average maturity with that of the Target Index, which was 24.4 years as of August 31, 2025.

The Fund is primarily intended for institutional investors that desire to

closely match long-term liabilities with a portfolio of U.S. Treasury

securities of similar long-term duration. Prospective investors are urged to

consult with their own advisors to determine whether the Fund is an

appropriate investment and the relationship of such an investment to their

overall investment program and financial and tax positions.

Principal Risks

As with any investment, an investment in the Fund could lose money over any time period. The Fund’s share price and total return may fluctuate, potentially

within a wide range. The principal risks of investing in the Fund are summarized below. Each of the following risks could affect the Fund’s performance:

• General Market Risk. The markets in which the Fund invests can be affected by a variety of factors. These factors, which can be real or perceived, may include economic, market, political, and regulatory conditions and developments as well as local, regional, or global events such as wars, military conflicts, natural disasters, and public health issues. In addition, investor sentiment and expectations regarding these factors can also impact the markets. Different parts of the market, including different industries and sectors as well as different types of securities, may react differently to factors that affect the market. These factors can contribute to market uncertainty, market volatility, and fluctuations in the value of the Fund’s investments, thereby resulting in potential losses to the Fund over short or long periods.

• Investing in Bond Markets. The Fund may be impacted by the general condition of the bond markets and by factors that affect bonds and bond issuers. For example, as a general rule, bond prices and interest rates move in opposite directions. When interest rates rise, bond prices tend to fall, and when interest rates fall, bond prices tend to go up. Bond income also is affected by changes in interest rates. Interest rates can rise or fall for a number of reasons, including, but not limited to, central bank monetary policy, inflationary or deflationary pressures, and changes in general market and economic conditions. Changing interest rates, including, but not limited to, rates that fall below zero, could have unpredictable effects on the overall market and may expose the bond markets in particular to heightened volatility and potential illiquidity. The degree to which the Fund is impacted by certain bond market risks may vary based on factors disclosed in its principal investment strategies, such as the types of bonds in which it invests and the overall credit quality, average maturity, and/or average duration of its bond holdings.

• Interest Rate Risk. During periods of rising interest rates, bond prices overall may decline, which could result in a decline in the Fund’s value. The prices of longer-term bonds are more sensitive to changes in interest rates than the prices of shorter-term bonds.

• Credit Risk. Credit risk refers to the chance that an issuer will default (fail to meet its credit obligations) or fail to make payments in a timely manner, which could result in a loss to the Fund. In addition, negative perceptions of an issuer’s ability to make payments can cause the price of a security to decline. While all debt securities are subject to credit risk to some extent, those with higher credit quality ratings generally pose less credit risk than those with lower credit quality ratings.

• Bond Liquidity Risk. If the Fund is unable to sell a security at an advantageous time or price, its returns may be reduced. There may be limited trading in the secondary market for certain debt securities, which could make them more difficult to value or sell.

• Treasury STRIPS. The Fund invests in Treasury STRIPS, which have prices that are more sensitive to interest rate changes than coupon-bearing bonds of similar maturity. Rising interest rates could cause the value of the Fund’s investments in Treasury STRIPS to decline significantly. It is expected that the Fund will be required to distribute income dividends to shareholders, but because Treasury STRIPS do not pay interest, the Fund does not receive cash interest payments on the Treasury STRIPS in which it invests. As a result, the Fund may need to liquidate assets, potentially at inopportune times, in order to satisfy its distribution requirements.

• Index Investing. The Fund is subject to risks associated with index investing. Because the Fund generally seeks to track the performance of the Target Index regardless of how the Target Index is performing, the Fund’s performance may be lower than it would be if it were actively managed. Additionally, because the Fund does not hold all of the securities included in the Target Index, it is subject to the risk that the representative sample of securities selected by the advisor will, in the aggregate, vary from the investment profile of the full Target Index. The performance of the Fund’s investments, in the aggregate, may not match the investment performance of the Target Index. This risk, known as tracking error risk, may be heightened during times of increased market volatility or under other unusual market conditions. The Fund also could be negatively impacted by changes to the Target Index made by the index provider or by errors made by the index provider. Any gains, losses, or costs associated with or resulting from an error made by the index provider will generally be borne by the Fund and, as a result, the Fund’s shareholders.

• ETF Share Trading. Vanguard ETF Shares (“ETF Shares”) are an exchanged-traded class of shares issued by certain Vanguard funds that represent an interest in the portfolio of securities held by the issuing fund. The Fund’s ETF Shares are listed for trading on NYSE Arca and individual investors may only buy and sell them on the secondary market at market prices. Although it is expected that the market price of an ETF Share typically will approximate its net asset value (NAV), there may be times when the market price of an ETF Share and its NAV differ significantly. Disruptions to creation and redemption transactions, the existence of significant market volatility, or potential lack of an active trading market for ETF Shares (including through a trading halt), as well as other factors, may result in ETF Shares trading significantly above (at a premium) or below (at a discount) the Fund’s NAV or the intraday value of the Fund’s holdings. Thus, you may pay more or less than NAV when you buy ETF Shares on the secondary market, and you may receive more or less than NAV when you sell those shares.

• Authorized Participants. Only Authorized Participants may engage in creation or redemption transactions directly with the Fund. The Fund has a limited number of financial institutions that may act as Authorized Participants. The Fund’s Authorized Participants are not obligated to engage in creation or

redemption transactions. To the extent that the Fund’s Authorized Participants are unable to or choose not to proceed with creation and/or redemption transactions with respect to the Fund and no other Authorized Participants step forward to engage in creation or redemption transactions with the Fund, the Fund’s ETF Shares may trade at a discount to NAV and possibly face trading halts and/or delisting.

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Annual Total Returns

The following bar chart and table show the Fund’s historical performance and are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund’s ETF Shares (based on NAV) has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the ETF Shares compare with those of a broad-based securities market index and one ore more additional indexes with similar investment characteristics as the Fund. Keep in mind that the Fund’s past performance (before and after taxes) does not indicate how the Fund will perform in the future. Updated performance information is available on our website at vanguard.com/performance.

Annual Total Returns — Vanguard Extended Duration Treasury Index Fund ETF Shares

The highest and lowest returns for a calendar quarter during the periods shown in the bar chart and the year-to-date return as of the most recent calendar quarter were:

	Total Return	Quarter
Highest	29.72 %	March 31, 2020
Lowest	-18.89 %	September 30, 2023
Year-to-Date Return	3.63 %	September 30, 2025

Average Annual Total Returns for Periods Ended December 31, 2024

	1 Year	5 Years	10 Years
Vanguard Extended Duration Treasury Index Fund ETF Shares
Based on NAV
Return Before Taxes	-13.27 %	-9.02 %	-2.34 %
Return After Taxes on Distributions	-14.79	-10.27	-3.71
Return After Taxes on Distributions and Sale of Fund Shares	-7.80	-6.74	-2.01
Based on Market Price
Return Before Taxes	-12.73	-8.99	-2.36
Bloomberg U.S. Treasury STRIPS 20-30 Year Equal Par Bond Index (reflects no deduction for fees, expenses, or taxes)	-12.97 %	-9.00 %	-2.30 %
Bloomberg U.S. Aggregate Float Adjusted Index (reflects no deduction for fees, expenses, or taxes)	1.33	-0.27	1.39

Actual after-tax returns depend on your tax situation and may differ from those shown in the preceding table. When after-tax returns are calculated, it is assumed that the shareholder was in the highest individual federal marginal income tax bracket at the time of each distribution of income or capital gains or upon redemption. State and local income taxes are not reflected in the calculations. Please note that after-tax returns are not relevant for a shareholder who holds fund shares in a tax-deferred account, such as an individual retirement account or a 401(k) plan. Also, figures captioned Return After Taxes on Distributions and Sale of Fund Shares may be higher than other figures for the same period if a capital loss occurs upon redemption and results in an assumed tax deduction for the shareholder.

Investment Advisor

The Vanguard Group, Inc. (Vanguard) through its wholly owned subsidiary, Vanguard Capital Management (VCM). VCM exercises portfolio management responsibilities for the Fund.

Portfolio Manager

Joshua C. Barrickman, CFA, Principal of Vanguard and Portfolio Manager at VCM. He has managed the Fund since 2013.

Purchase and Sale of Fund Shares

ETF Shares may only be bought and sold in the secondary market through a brokerage firm. The price you pay or receive for ETF Shares will be the prevailing market price, which may be more (premium) or less (discount) than the NAV of the shares. The brokerage firm may charge you a commission to execute the transaction. Unless imposed by your brokerage firm, there is no minimum dollar amount you must invest and no minimum number of shares you must buy. ETF Shares of the Fund cannot be directly purchased from or

redeemed with the Fund, except by certain authorized broker-dealers. These broker-dealers may purchase and redeem ETF Shares only in large blocks known as creation units, typically in exchange for baskets of securities.

An investor in ETF Shares may incur costs attributable to the difference between the highest price a buyer is willing to pay to purchase ETF Shares (bid) and the lowest price a seller is willing to accept for ETF Shares (ask) when buying or selling shares in the secondary market (bid-ask spread). Recent information about the Fund and its ETF Shares, including information on the Fund’s NAV, market price, premiums and discounts, and bid-ask spreads, is available online at vanguard.com.

Tax Information

The Fund’s distributions may be taxable as ordinary income or capital gains. If you are investing through a tax-advantaged account, such as an IRA or an employer-sponsored retirement or savings plan, special tax rules apply. You should consult your own tax advisor with respect to any particular U.S. or non-U.S. tax consequences of your investment in the Fund.

Payments to Financial Intermediaries

The Fund and its advisor do not pay financial intermediaries for sales of Fund shares.

CFA® is a registered trademark owned by CFA Institute.

“Bloomberg®” and the Bloomberg U.S. Treasury STRIPS 20-30 Year Equal Par Bond Index and Bloomberg U.S. Aggregate Float Adjusted Index (the “Indices”) are service marks of Bloomberg Finance L.P. and its affiliates, including Bloomberg Index Services Limited (“BISL”), the administrator of the Index (collectively, “Bloomberg”), and have been licensed for use for certain purposes by Vanguard.

Vanguard Extended Duration Treasury ETF (the “Fund”) is not sponsored, endorsed, sold or promoted by Bloomberg. Bloomberg does not make any representation or warranty, express or implied, to the owners of or counterparties to the Fund or any member of the public regarding the advisability of investing in securities or commodities generally or in the Fund particularly. The only relationship of Bloomberg to Vanguard is the licensing of certain trademarks, trade names and service marks and of the Indices, which are determined, composed and calculated by BISL without regard to Vanguard or the Fund. Bloomberg has no obligation to take the needs of Vanguard or the owners of the Fund into consideration in determining, composing or calculating the Indices. Bloomberg is not responsible for and has not participated in the determination of the timing, price, or quantities of the Fund to be issued. Bloomberg shall not have any obligation or liability, including, without limitation, to customers of the Fund, in connection with the administration, marketing or trading of the Fund.

BLOOMBERG DOES NOT GUARANTEE THE ACCURACY AND/OR THE COMPLETENESS OF THE INDICES OR ANY DATA RELATED THERETO AND SHALL HAVE NO LIABILITY FOR ANY ERRORS, OMISSIONS OR INTERRUPTIONS THEREIN. BLOOMBERG DOES NOT MAKE ANY WARRANTY, EXPRESS OR IMPLIED, AS TO RESULTS TO BE OBTAINED BY VANGUARD, OWNERS OF THE FUND OR ANY OTHER PERSON OR ENTITY FROM THE USE OF THE INDICES OR ANY DATA RELATED THERETO. BLOOMBERG DOES NOT MAKE ANY EXPRESS OR IMPLIED WARRANTIES AND EXPRESSLY DISCLAIMS ALL WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR USE WITH RESPECT TO THE INDICES OR ANY DATA RELATED THERETO. WITHOUT LIMITING ANY OF THE FOREGOING, TO THE MAXIMUM EXTENT ALLOWED BY LAW, BLOOMBERG, ITS LICENSORS, AND ITS AND THEIR RESPECTIVE EMPLOYEES, CONTRACTORS, AGENTS, SUPPLIERS, AND VENDORS SHALL HAVE NO LIABILITY OR RESPONSIBILITY WHATSOEVER FOR ANY INJURY OR DAMAGES—WHETHER DIRECT, INDIRECT, CONSEQUENTIAL, INCIDENTAL, PUNITIVE OR OTHERWISE—ARISING IN CONNECTION WITH THE FUND OR INDICES OR ANY DATA OR VALUES RELATING THERETO—WHETHER ARISING FROM THEIR NEGLIGENCE OR OTHERWISE, EVEN IF NOTIFIED OF THE POSSIBILITY THEREOF.

Vanguard Extended Duration Treasury Index Fund ETF Shares—Fund Number 930

To request additional information about the Fund, please visit vanguard.com or contact us at 866-499-8473.

Vanguard Marketing Corporation, Distributor.

SP 930 062026