Vanguard Mega Cap Index Fund Summary Prospectus

April 12, 2013

Institutional Shares

Vanguard Mega Cap Index Fund Institutional Shares (VMCTX)

The Fund’s statutory Prospectus and Statement of Additional Information dated April 12, 2013, 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 . You can also get this information at no cost by calling 800-662-7447 (if you are an individual investor) or 888-809-8102 (if you are a client of Vanguard‘s Institutional Division), or by sending an e-mail 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

The Fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization stocks in the United States.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold Institutional Shares of the Fund.

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

 

Annual Fund Operating Expenses

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

Management Expenses 0.05%
12b-1 Distribution Fee None
Other Expenses 0.03%
Total Annual Fund Operating Expenses 0.08%

 

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Example

The following example is intended to help you compare the cost of investing in the Fund’s Institutional Shares with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you invest $10,000 in the Fund’s shares. This example assumes that the Shares provide a return of 5% a year and that total annual fund operating expenses remain as stated in the preceding table. The results apply whether or not you redeem your investment at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

1 Year 3 Years 5 Years 10 Years
$8 $26 $45 $103

 

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 more taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the previous expense example, reduce the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 19%.

Primary Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the CRSP US Mega Cap Index. The Index is a free-float-adjusted, market-capitalization-weighted index designed to measure equity market performance of mega-capitalization stocks. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

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Primary Risks

An investment in the Fund could lose money over short or even long periods. You should expect the Fund’s share price and total return to fluctuate within a wide range, like the fluctuations of the overall stock market. The Fund is subject to the following risks, which could affect the Fund’s performance:

• Stock market risk , which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices. The Fund’s target index may, at times, become focused in stocks of a particular sector, category, or group of companies, which could cause the Fund to underperform the overall stock market.

• Investment style risk , which is the chance that returns from large-capitalization stocks will trail returns from the overall stock market. Large-cap stocks tend to go through cycles of doing better—or worse—than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

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 are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund‘s Institutional Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Institutional Shares compare with those of a relevant market index, which has investment characteristics similar to those of 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 or by calling Vanguard toll-free at 800-662-7447.

Annual Total Returns — Vanguard Mega Cap Index Fund Institutional Shares


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During the periods shown in the bar chart, the highest return for a calendar quarter was 15.55% (quarter ended June 30, 2009), and the lowest return for a quarter was –13.36% (quarter ended September 30, 2011).

Average Annual Total Returns for Periods Ended December 31, 2012    
    Since
    Inception
    (Feb. 22,
  1 Year 2008)
Vanguard Mega Cap Index Fund Institutional Shares    
Return Before Taxes 16.13% 3.37%
Return After Taxes on Distributions 15.73 3.03
Return After Taxes on Distributions and Sale of Fund Shares 11.01 2.83
MSCI US Large Cap 300 Index    
(reflects no deduction for fees, expenses, or taxes) 16.21% 3.42%

 

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 will 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.

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Investment Advisor

The Vanguard Group, Inc.

Portfolio Manager

Ryan E. Ludt, Principal of Vanguard. He has managed the Fund since its inception in 2007.

Purchase and Sale of Fund Shares

You may purchase or redeem shares online through our website ( vanguard.com) , by mail (The Vanguard Group, P.O. Box 1110, Valley Forge, PA 19482-1110), or by telephone (800-662-2739). The following table provides the Fund’s minimum initial and subsequent investment requirements.

Account Minimums Institutional Shares
To open and maintain an account $5 million
To add to an existing account Generally $100 (other than by Automatic Investment
  Plan, which has no established minimum)

 

Tax Information

The Fund’s distributions may be taxable as ordinary income or capital gain.

Payments to Financial Intermediaries

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

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Vanguard Mega Cap Index Fund Institutional Shares—Fund Number 828

Vanguard funds are not sponsored, endorsed, sold, or promoted by the University of Chicago or its Center for Research in Security Prices, and neither the University of Chicago nor its Center for Research in Security Prices makes any representation regarding the advisability of investing in the funds.

© 2013 The Vanguard Group, Inc. All rights reserved.
Vanguard Marketing Corporation, Distributor.

SPI 828 042013