SP 5481 Vanguard Materials Index Fund

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

Summary Prospectus

Vanguard Materials Index Fund

Admiral™ Shares

Vanguard Materials Index Fund Admiral Shares (VMIAX)

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 https://personal.vanguard.com/us/literature/reports/MFs. You can also obtain this information at no cost by calling 800-662-7447 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 Materials Index Fund (the “Fund”) seeks to track the performance of a benchmark index that measures the investment return of materials stocks.

Fees and Expenses

The following tables describe the fees and expenses you may pay if you buy, hold, and sell Admiral 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)


Sales Charge (Load) Imposed on Purchases	None
Purchase Fee	None
Sales Charge (Load) Imposed on Reinvested Dividends	None
Redemption Fee	None
Account Service Fee Per Year (for certain fund account balances below $5,000,000)	$25

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


Management Fees	0.08 %
12b-1 Distribution Fee	None
Other Expenses	0.01 %
Total Annual Fund Operating Expenses	0.09 %

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
$9	$29	$51	$115

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 7% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the MSCI US Investable Market Index (IMI)/Materials 25/50 (the “Target Index”), an index made up of stocks of large, mid-size, and small U.S. companies within the materials sector, as classified under the Global Industry Classification Standard (“GICS”). The GICS materials sector is made up of companies that manufacture chemicals, construction materials, glass, paper, forest products, and related packaging products, as well as metals, minerals, and mining companies, including producers of steel.

Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in the stocks that make up the Target Index. The Fund attempts to replicate the Target Index by investing all, or substantially all, of its assets in the stocks that make up the Target Index, holding each stock in approximately the same proportion as its weighting in the Target Index.

The Fund is considered nondiversified, as defined under the Investment Company Act of 1940, which means that it may invest a greater percentage of its assets in the securities of particular issuers as compared with diversified funds.

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 Equity Markets. The Fund invests in the equity markets. Equity markets have historically been cyclical, having periods of time when stock values rise and fall. Market volatility can lead to significant fluctuations in stock values, resulting in potential losses to the Fund.

• Market Capitalization (Market Cap). Companies are generally classified into three types of market cap depending on their size: small-, mid-, and large-cap. Companies can be further classified into micro- or mega-cap. Different factors can affect each market cap uniquely, and historically small- and mid-cap stocks have typically been more volatile due to the effects of changing economic conditions. Large companies may not reach the same levels of growth or performance as smaller companies, and they may be slower to react to competitive challenges. The performance of funds that invest in a subset of market caps could diverge from the performance of a fund that is focused on a broader representation of the stock market.

• 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. Although the Fund seeks to hold substantially all of the securities included in the Target Index, it may be unable to do so. In addition, the Fund could be prevented from holding one or more securities in the same proportion as in the 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.

• Nondiversified Funds. The Fund is considered a nondiversified fund as defined under the Investment Company Act of 1940. Nondiversified funds invest a greater percentage of their assets in a small number of issuers than diversified funds, their performance may be negatively impacted by relatively few securities or even a single security, and their shares may experience significant fluctuations in value.

• Materials Sector. Due to the Fund’s heavy investment in companies within the materials sector, its performance will be impacted by the general health of the sector. Companies in the materials sector can be negatively affected by various factors, including the volatility of commodity prices, exchange rates, and/or depletion of resources. Economic factors, government regulation, and

litigation including liabilities from environmental damage can also cause sector-wide harm.

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 Admiral Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Admiral Shares compare with those of a broad-based securities market index and one or 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 Materials Index Fund Admiral 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	26.14 %	June 30, 2020
Lowest	-27.96 %	March 31, 2020
Year-to-Date Return	10.42 %	September 30, 2025

Average Annual Total Returns for Periods Ended December 31, 2024

	1 Year	5 Years	10 Years
Vanguard Materials Index Fund Admiral Shares
Return Before Taxes	0.46 %	8.91 %	7.76 %
Return After Taxes on Distributions	0.08	8.44	7.28
Return After Taxes on Distributions and Sale of Fund Shares	0.57	7.00	6.20
MSCI US IMI/Materials 25/50 (reflects no deduction for fees, expenses, or taxes)	0.54 %	9.01 %	7.84 %
MSCI US Investable Market 2500 Index (reflects no deduction for fees, expenses, or taxes)	23.82	14.02	12.64

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 Portfolio Management (VPM) exercises portfolio management responsibilities for the Fund.

Portfolio Managers

Kenny Narzikul, CFA, Portfolio Manager at VPM. He has co-managed the Fund since 2023.

Jena Stenger, Portfolio Manager at VPM. She has co-managed the Fund since 2025.

Purchase and Sale of Fund Shares

If you invest directly with Vanguard, you may purchase or redeem shares online through our website (vanguard.com), by mail (The Vanguard Group, P.O. Box 982901, El Paso, TX 79998-2901), or by telephone (800-662-2739). The minimum investment amount required to open a Fund account for Admiral Shares is generally $100,000. The minimum investment amount required to add to an existing Fund account is generally $1.

Financial intermediaries, institutional clients, and Vanguard-advised clients should contact Vanguard for information on special eligibility rules that may apply to them regarding Admiral Shares. If you invest in Vanguard fund shares indirectly through an intermediary (including investing in shares through a brokerage account offered by Vanguard Brokerage Services®), please contact that firm directly for more information regarding your eligibility. If you invest in Vanguard fund shares through an employer-sponsored retirement or savings plan, your plan administrator or your benefits office can provide you with detailed information on how you can invest through your plan.

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.

THIS FUND IS NOT SPONSORED, ENDORSED, SOLD OR PROMOTED BY MSCI INC. (“MSCI”), ANY OF ITS AFFILIATES, ANY OF ITS DIRECT OR INDIRECT INFORMATION PROVIDERS OR ANY OTHER THIRD PARTY INVOLVED IN, OR RELATED TO, COMPILING, COMPUTING OR CREATING ANY MSCI INDEX (COLLECTIVELY, THE “MSCI PARTIES”). THE MSCI INDEXES ARE THE EXCLUSIVE PROPERTY OF MSCI. MSCI AND THE MSCI INDEX NAMES ARE SERVICE MARK(S) OF MSCI OR ITS AFFILIATES AND HAVE BEEN LICENSED FOR USE FOR CERTAIN PURPOSES BY VANGUARD. NONE OF THE MSCI PARTIES MAKES ANY REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, TO THE OWNERS OF THIS FUND OR ANY MEMBER OF THE PUBLIC REGARDING THE ADVISABILITY OF INVESTING IN FUNDS GENERALLY OR IN THIS FUND PARTICULARLY OR THE ABILITY OF ANY MSCI INDEX TO TRACK CORRESPONDING STOCK MARKET PERFORMANCE. MSCI OR ITS AFFILIATES ARE THE LICENSORS OF CERTAIN TRADEMARKS, SERVICE MARKS AND TRADE NAMES AND OF THE MSCI INDEXES WHICH ARE DETERMINED, COMPOSED AND CALCULATED BY MSCI WITHOUT REGARD TO THIS FUND OR THE ISSUER OR OWNER OF THIS FUND. NONE OF THE MSCI PARTIES HAS ANY OBLIGATION TO TAKE THE NEEDS OF THE ISSUERS OR OWNERS OF THIS FUND INTO CONSIDERATION IN DETERMINING, COMPOSING OR CALCULATING THE MSCI INDEXES. NONE OF THE MSCI PARTIES IS RESPONSIBLE FOR OR HAS PARTICIPATED IN THE DETERMINATION OF THE TIMING OF, PRICES AT, OR QUANTITIES OF THIS FUND TO BE ISSUED OR IN THE DETERMINATION OR CALCULATION OF THE CONSIDERATION INTO WHICH THIS FUND IS REDEEMABLE. NONE OF THE MSCI PARTIES HAS ANY OBLIGATION OR LIABILITY TO THE OWNERS OF THIS FUND IN CONNECTION WITH THE ADMINISTRATION, MARKETING OR OFFERING OF THIS FUND.

ALTHOUGH MSCI SHALL OBTAIN INFORMATION FOR INCLUSION IN OR FOR USE IN THE CALCULATION OF THE MSCI INDEXES FROM SOURCES WHICH MSCI CONSIDERS RELIABLE, NONE OF THE MSCI PARTIES WARRANTS OR GUARANTEES THE ORIGINALITY, ACCURACY AND/OR THE COMPLETENESS OF ANY MSCI INDEX OR ANY DATA INCLUDED THEREIN. NONE OF THE MSCI PARTIES MAKES ANY WARRANTY, EXPRESS OR IMPLIED, AS TO RESULTS TO BE OBTAINED BY LICENSEE, LICENSEE’S CUSTOMERS OR COUNTERPARTIES, ISSUERS OF THIS FUND, OWNERS OF THIS FUND, OR ANY OTHER PERSON OR ENTITY, FROM THE USE OF ANY MSCI INDEX OR ANY DATA INCLUDED THEREIN IN CONNECTION WITH THE RIGHTS LICENSED HEREUNDER OR FOR ANY OTHER USE. NONE OF THE MSCI PARTIES SHALL HAVE ANY LIABILITY FOR ANY ERRORS, OMISSIONS OR INTERRUPTIONS OF OR IN CONNECTION WITH ANY MSCI INDEX OR ANY DATA INCLUDED THEREIN. FURTHER, NONE OF THE MSCI PARTIES MAKES ANY EXPRESS OR IMPLIED WARRANTIES OF ANY KIND, AND THE MSCI PARTIES HEREBY EXPRESSLY DISCLAIM ALL WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, WITH RESPECT TO ANY MSCI INDEX AND ANY DATA INCLUDED THEREIN. WITHOUT LIMITING ANY OF THE FOREGOING, IN NO EVENT SHALL ANY OF THE MSCI PARTIES HAVE ANY LIABILITY FOR ANY DIRECT, INDIRECT, SPECIAL, PUNITIVE, CONSEQUENTIAL OR ANY OTHER DAMAGES (INCLUDING WITHOUT LIMITATION LOST PROFITS) EVEN IF NOTIFIED OF THE POSSIBILITY OF SUCH DAMAGES.

Vanguard Materials Index Fund Admiral Shares—Fund Number 5481

To request additional information about the Fund, please visit vanguard.com or contact us at 800-662-7447.

Vanguard Marketing Corporation, Distributor.

SP 5481 062026