VANGUARD INSTITUTIONAL INDEX FUND
485BPOS, 2000-04-06
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- --------------------------------------------------------------------------------


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                    FORM N-1A

                 REGISTRATION STATEMENT (NO. 33-34494) UNDER THE
                             SECURITIES ACT OF 1933

                           PRE-EFFECTIVE AMENDMENT NO.


                         POST-EFFECTIVE AMENDMENT NO. 19

                                       AND

                        REGISTRATION STATEMENT UNDER THE
                         INVESTMENT COMPANY ACT OF 1940

                                AMENDMENT NO. 20


                       VANGUARD INSTITUTIONAL INDEX FUND
        (EXACT NAME OF REGISTRANT AS SPECIFIED IN DECLARATION OF TRUST)

                     P.O. BOX 2600, VALLEY FORGE, PA 19482
                    (ADDRESS OF PRINCIPAL EXECUTIVE OFFICE)

                  REGISTRANT'S TELEPHONE NUMBER (610) 669-1000

                           R. GREGORY BARTON, ESQUIRE
                                  P.O. BOX 876
                             VALLEY FORGE, PA 19482


                 APPROXIMATE DATE OF PROPOSED PUBLIC OFFERING:
   AS SOON AS PRACTICABLE AFTER THIS REGISTRATION STATEMENT BECOMES EFFECTIVE.

                IT IS PROPOSED THAT THIS FILING BECOME EFFECTIVE:
            ON APRIL 21, 2000 PURSUANT TO PARAGRAPH (B) OF RULE 485.


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<PAGE>

                              VANGUARD(R) INSTITUTIONAL INDEX FUND
                              INSTITUTIONAL SHARES AND INSTITUTIONAL PLUS SHARES

                              VANGUARD(R) U.S. STOCK INDEX FUNDS
                              INSTITUTIONAL SHARES

                              Prospectus
                              April 21, 2000

VANGUARD INSTITUTIONAL
INDEX FUND

 INSTITUTIONAL SHARES

 INSTITUTIONAL PLUS
 SHARES

VANGUARD U.S. STOCK
INDEX FUNDS
INSTITUTIONAL SHARES OF:

 VANGUARD TOTAL STOCK
 MARKET INDEX FUND

 VANGUARD EXTENDED
 MARKET INDEX FUND

 VANGUARD MID-CAP
 INDEX FUND

 VANGUARD SMALL-CAP
 INDEX FUND

 VANGUARD VALUE
 INDEX FUND

 VANGUARD SMALL-CAP
 VALUE INDEX FUND

 VANGUARD GROWTH
 INDEX FUND

 VANGUARD SMALL-CAP
 GROWTH INDEX FUND

This prospectus contains
financial data for the
Funds through the
fiscal year ended
December 31, 1999.


                                                         [THE VANGUARD GROUP(R)]

<PAGE>


VANGUARD INSTITUTIONAL INDEX FUND
VANGUARD U.S. STOCK INDEX FUNDS
Prospectus
April 21, 2000


<TABLE>
<CAPTION>
- ------------------------------------------------------------------------------------------------
CONTENTS
- ------------------------------------------------------------------------------------------------
<S>                                                     <C>
1 FUND PROFILES                                         28 MORE ON THE FUNDS

   1 VANGUARD INSTITUTIONAL INDEX FUND                  33 THE FUNDS AND VANGUARD
     INSTITUTIONAL AND INSTITUTIONAL PLUS SHARES
   4 VANGUARD TOTAL STOCK MARKET INDEX FUND             33 INVESTMENT ADVISER
     INSTITUTIONAL SHARES
   7 VANGUARD EXTENDED MARKET INDEX FUND                34 DIVIDENDS, CAPITAL GAINS, AND TAXES
     INSTITUTIONAL SHARES
  10 VANGUARD MID-CAP INDEX FUND                        34 SHARE PRICE
     INSTITUTIONAL SHARES
  13 VANGUARD SMALL-CAP INDEX FUND                      36 FINANCIAL HIGHLIGHTS
     INSTITUTIONAL SHARES
  16 VANGUARD VALUE INDEX FUND                          42 INVESTING WITH VANGUARD
     INSTITUTIONAL SHARES                                  42 SERVICES AND ACCOUNT FEATURES
  19 VANGUARD SMALL-CAP VALUE INDEX FUND                   43 TYPES OF ACCOUNTS
     INSTITUTIONAL SHARES                                  43 BUYING SHARES
  22 VANGUARD GROWTH INDEX FUND                            45 REDEEMING SHARES
     INSTITUTIONAL SHARES                                  48 TRANSFERRING REGISTRATION
  25 VANGUARD SMALL-CAP GROWTH INDEX FUND                  48 FUND AND ACCOUNT UPDATES
     INSTITUTIONAL SHARES
                                                        49 MANDATORY CONVERSION TO INSTITUTIONAL
                                                           OR INVESTOR SHARES

                                                        GLOSSARY (inside back cover)
- ------------------------------------------------------------------------------------------------
</TABLE>

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WHY READING THIS PROSPECTUS IS IMPORTANT
This  prospectus  explains  the  objectives, risks,  and  strategies  of certain
Vanguard index funds. To highlight  terms and concepts  important to mutual fund
investors,  we have provided "Plain Talk(R)" explanations along the way. Reading
the  prospectus  will  help you to decide  which  Funds,  if any,  are the right
investments for you. We suggest that you keep it for future reference.
- --------------------------------------------------------------------------------

- --------------------------------------------------------------------------------
OTHER CLASSES OF SHARES AND OTHER PROSPECTUSES
Vanguard  currently  offers nine U.S.  stock index  funds.  Each of these funds,
other than Vanguard 500 Index Fund, issues two classes of shares:  Institutional
Shares and  Investor  Shares.  Institutional  Shares are  intended  for  persons
investing  at least $10 million who  generally do not require  special  employee
benefit services. For those wishing to invest at least $10 million in an S&P 500
index fund and who generally do not require special employee  benefit  services,
Vanguard  offers  the  Vanguard  Institutional  Index  Fund.  This  Fund  issues
Institutional   Shares  for  those   investing  less  than  $200  million,   and
Institutional Plus Shares for those investing $200 million or more.

This  prospectus  describes  the  Institutional  Shares  offered  by each of the
Vanguard U.S. Stock Index Funds (other than Vanguard 500 Index Fund,  which does
not offer Institutional  Shares) and the Institutional  Shares and Institutional
Plus Shares offered by Vanguard  Institutional Index Fund. If you are interested
in  purchasing  Investor  Shares,  please call  Vanguard at  1-800-662-7447  (or
1-800-523-1036  if  you  will  be  purchasing   through  an   employer-sponsored
retirement plan).

Note that the Funds'  separate  share  classes  have  different  expenses;  as a
result, their investment performances will vary.
- --------------------------------------------------------------------------------



NEITHER  THE  SECURITIES  AND  EXCHANGE  COMMISSION  NOR  ANY  STATE  SECURITIES
COMMISSION HAS APPROVED OR  DISAPPROVED  OF THESE  SECURITIES OR PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.
<PAGE>

                                                                               1

FUND   PROFILE--VANGUARD(R)   INSTITUTIONAL   INDEX   FUND   INSTITUTIONAL   AND
INSTITUTIONAL PLUS SHARES

The following profile  summarizes key features of Vanguard  Institutional  Index
Fund Institutional and Institutional Plus Shares.

INVESTMENT OBJECTIVE
The Fund seeks to match the  performance of a benchmark  index that measures the
investment return of large-capitalization stocks.

INVESTMENT STRATEGIES

The Fund employs a passive management strategy designed to track the performance
of the  Standard & Poor's 500 Index,  which is  dominated by the stocks of large
U.S. companies.


PRIMARY RISKS
- -    THE FUND'S TOTAL RETURN, LIKE STOCK PRICES GENERALLY, WILL FLUCTUATE WITHIN
     A WIDE  RANGE,  SO AN  INVESTOR  COULD  LOSE  MONEY OVER SHORT OR EVEN LONG
     PERIODS.  Stock  markets  tend to move in  cycles,  with  periods of rising
     prices and periods of falling prices.
- -    The Fund is also subject to investment style risk, which is the chance that
     returns  from  large-capitalization  stocks will trail  returns  from other
     asset classes or the overall stock market. Large-capitalization stocks tend
     to go through cycles of doing  better--or  worse--than  the stock market in
     general.  These periods  have,  in the past,  lasted for as long as several
     years.

PERFORMANCE/RISK INFORMATION

The bar chart and table below  provide an indication of the risk of investing in
the Fund. The bar chart shows the performance of the Fund's Institutional Shares
in each calendar year since the Fund's inception.  (Performance  information for
the Institutional Plus Shares would be substantially  similar,  since both share
classes represent the same portfolio of securities; their returns differ only to
the extent that the expenses of the two classes differ.) The table shows how the
Fund's  average  annual total returns for one and five calendar  years and since
inception  (for  Institutional  Shares)  and for one  calendar  year  and  since
inception (for  Institutional  Plus Shares) compare with those of the index that
the Fund seeks to track.  Keep in mind that the Fund's past performance does not
indicate how it will perform in the future.

- --------------------------------------------------------------------------------
                              ANNUAL TOTAL RETURNS
- --------------------------------------------------------------------------------
                              1991          30.34%
                              1992           7.54%
                              1993          10.02%
                              1994           1.31%
                              1995          37.60%
                              1996          23.06%
                              1997          33.36%
                              1998          28.79%
                              1999          21.17%
- --------------------------------------------------------------------------------

<PAGE>

2


     During the period shown in the bar chart, the highest return for a calendar
quarter was 14.99% (quarter ended December 31, 1999) and the lowest return for a
quarter was -6.23% (quarter ended September 30, 1999).

- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                                                    SINCE
                                    1 YEAR        5 YEARS         INCEPTION*
- --------------------------------------------------------------------------------
Vanguard Institutional Index Fund
  Institutional Shares              21.17%         28.65%           19.10%
S&P 500 Index                       21.04          28.56            19.09
- --------------------------------------------------------------------------------
*July 31, 1990.
- --------------------------------------------------------------------------------

- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                                                    SINCE
                                                  1 YEAR          INCEPTION*
- --------------------------------------------------------------------------------
Vanguard Institutional Index Fund
  Institutional Plus Shares                       21.21%            23.08%
S&P 500 Index                                     21.04             22.90
- --------------------------------------------------------------------------------
*July 7, 1997.
- --------------------------------------------------------------------------------

FEES AND EXPENSES
The following  table  describes the fees and expenses you may pay if you buy and
hold shares of the Fund. The expenses shown under Annual Fund Operating Expenses
are based upon those incurred in the fiscal year ended December 31, 1999.

      SHAREHOLDER FEES* (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                 None
      Transaction Fee on Purchases:                             None**
      Sales Charge (Load) Imposed on Reinvested Dividends:      None
      Redemption Fee:                                           None
      Exchange Fee:                                             None

      INSTITUTIONAL SHARES
      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the
      Fund's assets)
      Management Expenses:                                     0.06%
      12b-1 Distribution Fee:                                   None
      Other Expenses:                                             0%
       TOTAL ANNUAL FUND OPERATING EXPENSES:                   0.06%

      INSTITUTIONAL PLUS SHARES
      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the
      Fund's assets)
      Management Expenses:                                    0.025%
      12b-1 Distribution Fee:                                   None
      Other Expenses:                                             0%
       TOTAL ANNUAL FUND OPERATING EXPENSES:                  0.025%

       *Applies to both Institutional and Institutional Plus Shares.
      **The Fund reserves the right to deduct a transaction fee from
        future purchases of shares.


<PAGE>

                                                                               3

     The following example is intended to help you compare the cost of investing
in the Fund 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.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.


- --------------------------------------------------------------------------------
                            1 YEAR   3 YEARS   5 YEARS    10 YEARS
- --------------------------------------------------------------------------------
Institutional Shares          $6       $19       $34        $77
Institutional Plus Shares      3         8        14         32
- --------------------------------------------------------------------------------


     THIS  EXAMPLE  SHOULD NOT BE  CONSIDERED  TO REPRESENT  ACTUAL  EXPENSES OR
PERFORMANCE  FROM THE PAST OR FOR THE  FUTURE.  ACTUAL  FUTURE  EXPENSES  MAY BE
HIGHER OR LOWER THAN THOSE SHOWN.


- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION--INSTITUTIONAL SHARES

DIVIDENDS AND CAPITAL GAINS                        NEWSPAPER ABBREVIATION
Dividends are distributed quarterly in March,      InstIdx
June, September, and December; capital gains, if
any, are distributed annually in December          VANGUARD FUND NUMBER
                                                   094
INVESTMENT ADVISER
The Vanguard Group, Valley Forge, Pa.,             CUSIP NUMBER
since inception                                    922040100

INCEPTION DATE                                     TICKER SYMBOL
July 31, 1990                                      VINIX

NET ASSETS AS OF DECEMBER 31, 1999
$28.91 billion
- --------------------------------------------------------------------------------

- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION--INSTITUTIONAL PLUS SHARES

DIVIDENDS AND CAPITAL GAINS                        NEWSPAPER ABBREVIATION
Dividends are distributed quarterly in March,      InstPlus
June, September, and December; capital gains, if
any, are distributed annually in December          VANGUARD FUND NUMBER
                                                   854
INVESTMENT ADVISER
The Vanguard Group, Valley Forge, Pa.,             CUSIP NUMBER
since inception                                    922040209

INCEPTION DATE                                     TICKER SYMBOL
July 7, 1997                                       VIIIX

NET ASSETS AS OF DECEMBER 31, 1999
$6.86 billion
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<PAGE>

4

FUND PROFILE--VANGUARD(R) TOTAL STOCK MARKET INDEX FUND INSTITUTIONAL SHARES

The following  profile  summarizes  key features of Vanguard  Total Stock Market
Index Fund Institutional Shares.

INVESTMENT OBJECTIVE
The Fund seeks to match the  performance of a benchmark  index that measures the
investment return of the overall stock market.

INVESTMENT STRATEGIES

The Fund employs a passive management strategy designed to track the performance
of the Wilshire 5000 Total Market Index,  which consists of all the U.S.  common
stocks  regularly  traded on the New York and American  Stock  Exchanges and the
Nasdaq  over-the-counter  market.  The Fund  invests  in  selected  stocks  that
comprise the Index.


PRIMARY RISK
THE FUND'S TOTAL RETURN,  LIKE STOCK PRICES  GENERALLY,  WILL FLUCTUATE WITHIN A
WIDE  RANGE,  SO AN INVESTOR  COULD LOSE MONEY OVER SHORT OR EVEN LONG  PERIODS.
Stock markets tend to move in cycles,  with periods of rising prices and periods
of falling prices.

PERFORMANCE/RISK INFORMATION
The bar chart and table below  provide an indication of the risk of investing in
the Fund. The bar chart shows the Fund's performance in each calendar year since
inception of the Institutional  class of shares.  The table shows how the Fund's
average annual total returns for one calendar year and since  inception  compare
with  those of the index  that the Fund  seeks to  track.  Keep in mind that the
Fund's past performance does not indicate how it will perform in the future.


- --------------------------------------------------------------------------------
                              ANNUAL TOTAL RETURNS
- --------------------------------------------------------------------------------
                              1998          23.37%
                              1999          23.93%
- --------------------------------------------------------------------------------

     During the period shown in the bar chart, the highest return for a calendar
quarter was 21.55% (quarter ended December 31, 1998) and the lowest return for a
quarter was -12.05% (quarter ended September 30, 1998).

<PAGE>

                                                                               5

- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                                                  SINCE
                                          1 YEAR                INCEPTION*
- --------------------------------------------------------------------------------
Vanguard Total Stock Market Index Fund
  Institutional Shares                    23.93%                  22.64%
Wilshire 5000 Index                       23.77                   22.69
- --------------------------------------------------------------------------------
*July 7, 1997.
- --------------------------------------------------------------------------------

FEES AND EXPENSES
The following  table  describes the fees and expenses you may pay if you buy and
hold  Institutional  Shares of the Fund.  The  expenses  shown under Annual Fund
Operating  Expenses  are based upon  those  incurred  in the  fiscal  year ended
December 31, 1999.

      SHAREHOLDER FEES (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                 None
      Transaction Fee on Purchases:                             None*
      Sales Charge (Load) Imposed on Reinvested Dividends:      None
      Redemption Fee:                                           None
      Exchange Fee:                                             None

      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the
      Fund's assets)
      Management Expenses:                                     0.08%
      12b-1 Distribution Fee:                                   None
      Other Expenses:                                          0.02%
       TOTAL ANNUAL FUND OPERATING EXPENSES:                   0.10%

      *The Fund reserves the right to deduct a transaction fee from future
       purchases of shares.


     The following example is intended to help you compare the cost of investing
in the Fund 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.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.


- --------------------------------------------------------------------------------
                 1 YEAR      3 YEARS    5 YEARS      10 YEARS
- --------------------------------------------------------------------------------
                  $10          $32        $56          $128
- --------------------------------------------------------------------------------


     THIS  EXAMPLE  SHOULD NOT BE  CONSIDERED  TO REPRESENT  ACTUAL  EXPENSES OR
PERFORMANCE  FROM THE PAST OR FOR THE  FUTURE.  ACTUAL  FUTURE  EXPENSES  MAY BE
HIGHER OR LOWER THAN THOSE SHOWN.
<PAGE>

6


- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION

DIVIDENDS AND CAPITAL GAINS                        NEWSPAPER ABBREVIATION
Dividends are distributed quarterly in March,      TotStIst
June, September, and December; capital gains, if
any, are distributed annually in December          VANGUARD FUND NUMBER
                                                   855
INVESTMENT ADVISER
The Vanguard Group, Valley Forge, Pa.,             CUSIP NUMBER
since inception                                    922908801

INCEPTION DATE                                     TICKER SYMBOL
July 7, 1997                                       VITSX

NET ASSETS (ALL SHARE CLASSES) AS OF
DECEMBER 31, 1999
$22.1 billion
- --------------------------------------------------------------------------------

<PAGE>

                                                                               7

FUND PROFILE--VANGUARD(R) EXTENDED MARKET INDEX FUND INSTITUTIONAL SHARES

The following profile  summarizes key features of Vanguard Extended Market Index
Fund Institutional Shares.

INVESTMENT OBJECTIVE
The Fund seeks to match the  performance of a benchmark  index that measures the
investment return of mid- and small-capitalization stocks.

INVESTMENT STRATEGIES

The Fund employs a passive management strategy designed to track the performance
of the Wilshire 4500 Completion Index, a broadly  diversified index of stocks of
medium-size  and small U.S.  companies.  The Wilshire 4500 Index contains all of
the U.S.  common  stocks  regularly  traded on the New York and  American  Stock
Exchanges and the Nasdaq  over-the-counter  market, except those stocks included
in the S&P 500 Index.  The Fund  invests in selected  stocks that  comprise  the
Index.


PRIMARY RISKS
- -    THE FUND'S TOTAL RETURN, LIKE STOCK PRICES GENERALLY, WILL FLUCTUATE WITHIN
     A WIDE  RANGE,  SO AN  INVESTOR  COULD  LOSE  MONEY OVER SHORT OR EVEN LONG
     PERIODS.  Stock  markets  tend to move in  cycles,  with  periods of rising
     prices and periods of falling prices.
- -    The Fund is also subject to investment style risk, which is the chance that
     returns from mid- or  small-capitalization  stocks will trail  returns from
     other asset classes or the overall stock market.  Small- and mid-cap stocks
     historically  have been more  volatile in price than the  large-cap  stocks
     that dominate the S&P 500 Index,  and perform  differently than the overall
     stock market.

PERFORMANCE/RISK INFORMATION
The bar chart and table below  provide an indication of the risk of investing in
the Fund. The bar chart shows the Fund's performance in each calendar year since
inception of the Institutional  class of shares.  The table shows how the Fund's
average annual total returns for one calendar year and since  inception  compare
with  those of the index  that the Fund  seeks to  track.  Keep in mind that the
Fund's past performance does not indicate how it will perform in the future.


- --------------------------------------------------------------------------------
                              ANNUAL TOTAL RETURNS
- --------------------------------------------------------------------------------
                              1998           8.45%
                              1999          36.45%
- --------------------------------------------------------------------------------
Return figures do not reflect the transaction fee on purchases prior to April 1,
2000.
- --------------------------------------------------------------------------------

<PAGE>

8


     During the period shown in the bar chart, the highest return for a calendar
quarter was 29.63% (quarter ended December 31, 1999) and the lowest return for a
quarter was -18.66% (quarter ended September 30, 1998).

- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                             1 YEAR        SINCE INCEPTION*
- --------------------------------------------------------------------------------
Vanguard Extended Market Index Fund
  Institutional Shares**                     36.45%             22.47%
Wilshire 4500 Index                          35.37              22.26
- --------------------------------------------------------------------------------
 *July 7, 1997.
**Return figures do not reflect the transaction fee on purchases prior to
  April 1, 2000.
- --------------------------------------------------------------------------------

FEES AND EXPENSES
The following  table  describes the fees and expenses you may pay if you buy and
hold  Institutional  Shares of the Fund.  The  expenses  shown under Annual Fund
Operating  Expenses  are based upon  those  incurred  in the  fiscal  year ended
December 31, 1999.

      SHAREHOLDER FEES (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                 None
      Transaction Fee on Purchases:                             None*
      Sales Charge (Load) Imposed on Reinvested Dividends:      None
      Redemption Fee:                                           None
      Exchange Fee:                                             None

      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the
      Fund's assets)
      Management Expenses:                                     0.07%
      12b-1 Distribution Fee:                                   None
      Other Expenses:                                          0.03%
       TOTAL ANNUAL FUND OPERATING EXPENSES:                   0.10%

      *The Fund reserves the right to deduct a transaction fee from future
       purchases of shares.


     The following example is intended to help you compare the cost of investing
in the Fund 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.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.


- --------------------------------------------------------------------------------
                      1 YEAR      3 YEARS    5 YEARS      10 YEARS
- --------------------------------------------------------------------------------
                       $10          $32        $56          $128
- --------------------------------------------------------------------------------


     THIS  EXAMPLE  SHOULD NOT BE  CONSIDERED  TO REPRESENT  ACTUAL  EXPENSES OR
PERFORMANCE  FROM THE PAST OR FOR THE  FUTURE.  ACTUAL  FUTURE  EXPENSES  MAY BE
HIGHER OR LOWER THAN THOSE SHOWN.
<PAGE>

                                                                               9


- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION

DIVIDENDS AND CAPITAL GAINS                    NEWSPAPER ABBREVIATION
Distributed annually in December               ExtndIst

INVESTMENT ADVISER                             VANGUARD FUND NUMBER
The Vanguard Group, Valley Forge, Pa.,         856
since inception
                                               CUSIP NUMBER
INCEPTION DATE                                 922908884
July 7, 1997
                                               TICKER SYMBOL
NET ASSETS (ALL SHARE CLASSES) AS OF           VIEIX
DECEMBER 31, 1999
$5.1 billion
- --------------------------------------------------------------------------------

<PAGE>

10

FUND PROFILE--VANGUARD(R) MID-CAP INDEX FUND INSTITUTIONAL SHARES

The following  profile  summarizes  key features of Vanguard  Mid-Cap Index Fund
Institutional Shares.

INVESTMENT OBJECTIVE
The Fund seeks to match the  performance of a benchmark  index that measures the
investment return of mid-capitalization stocks.

INVESTMENT STRATEGIES
The Fund employs a passive management strategy designed to track the performance
of the  Standard  &  Poor's  MidCap  400  Index,  which is made up of a group of
medium-size  U.S.  companies.  The Fund invests in the stocks that  comprise the
Index.

PRIMARY RISKS
- -    THE FUND'S TOTAL RETURN, LIKE STOCK PRICES GENERALLY, WILL FLUCTUATE WITHIN
     A WIDE  RANGE,  SO AN  INVESTOR  COULD  LOSE  MONEY OVER SHORT OR EVEN LONG
     PERIODS.  Stock  markets  tend to move in  cycles,  with  periods of rising
     prices and periods of falling prices.
- -    The Fund is also subject to investment style risk, which is the chance that
     returns from mid-capitalization  stocks will trail returns from other asset
     classes or the overall stock market.  Mid-cap stocks historically have been
     more volatile in price than the large-cap  stocks that dominate the S&P 500
     Index, and perform differently than the overall stock market.

PERFORMANCE/RISK INFORMATION
The bar chart and table below  provide an indication of the risk of investing in
the Fund.  The bar chart shows the Fund's  performance  in the one full calendar
year since inception of the Institutional  class of shares.  The table shows how
the Fund's average annual total returns for one year and since inception compare
with  those of the index  that the Fund  seeks to  track.  Keep in mind that the
Fund's past performance does not indicate how it will perform in the future.


- --------------------------------------------------------------------------------
                              ANNUAL TOTAL RETURN
- --------------------------------------------------------------------------------
                              1999         15.41%
- --------------------------------------------------------------------------------

     During the period shown in the bar chart, the highest return for a calendar
quarter was 17.26% (quarter ended December 31, 1999) and the lowest return for a
quarter was -8.20% (quarter ended September 30, 1999).

<PAGE>

                                                                              11


- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                                  1 YEAR        SINCE INCEPTION*
- --------------------------------------------------------------------------------
Vanguard Mid-Cap Index Fund Institutional Shares  15.41%             15.03%
S&P's MidCap 400 Index                            14.72              14.12
- --------------------------------------------------------------------------------
*May 21, 1998.
- --------------------------------------------------------------------------------

FEES AND EXPENSES
The following  table  describes the fees and expenses you may pay if you buy and
hold  Institutional  Shares of the Fund.  The  expenses  shown under Annual Fund
Operating  Expenses  are based upon  those  incurred  in the  fiscal  year ended
December 31, 1999.

      SHAREHOLDER FEES (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                 None
      Transaction Fee on Purchases:                             None*
      Sales Charge (Load) Imposed on Reinvested Dividends:      None
      Redemption Fee:                                           None
      Exchange Fee:                                             None

      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the
      Fund's assets)
      Management Expenses:                                     0.10%
      12b-1 Distribution Fee:                                   None
      Other Expenses:                                          0.02%
       TOTAL ANNUAL FUND OPERATING EXPENSES:                   0.12%

      *The Fund reserves the right to deduct a transaction fee from future
       purchases of shares.


     The following example is intended to help you compare the cost of investing
in the Fund 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.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.


- --------------------------------------------------------------------------------
                1 YEAR      3 YEARS    5 YEARS      10 YEARS
- --------------------------------------------------------------------------------
                  $12         $39        $68          $154
- --------------------------------------------------------------------------------


     THIS  EXAMPLE  SHOULD NOT BE  CONSIDERED  TO REPRESENT  ACTUAL  EXPENSES OR
PERFORMANCE  FROM THE PAST OR FOR THE  FUTURE.  ACTUAL  FUTURE  EXPENSES  MAY BE
HIGHER OR LOWER THAN THOSE SHOWN.
<PAGE>

12


- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION

DIVIDENDS AND CAPITAL GAINS                    NEWSPAPER ABBREVIATION
Distributed annually in December               MidCpIst

INVESTMENT ADVISER                             VANGUARD FUND NUMBER
The Vanguard Group, Valley Forge, Pa.,         864
since inception
                                               CUSIP NUMBER
INCEPTION DATE                                 922908835
May 21, 1998
                                               TICKER SYMBOL
NET ASSETS (ALL SHARE CLASSES) AS OF           VMCIX
DECEMBER 31, 1999
$748 million
- --------------------------------------------------------------------------------

<PAGE>

                                                                              13

FUND PROFILE--VANGUARD(R) SMALL-CAP INDEX FUND INSTITUTIONAL SHARES

The following profile  summarizes key features of Vanguard  Small-Cap Index Fund
Institutional Shares.

INVESTMENT OBJECTIVE
The Fund seeks to match the  performance of a benchmark  index that measures the
investment return of small-capitalization stocks.

INVESTMENT STRATEGIES
The Fund employs a passive management strategy designed to track the performance
of the Russell 2000 Small Stock Index, which is made up of the stocks of smaller
U.S.  companies.  The  Russell  2000 Index is  comprised  of the 2,000  smallest
companies out of the 3,000 largest U.S. companies.  The Fund invests in selected
stocks that comprise the Index.

PRIMARY RISKS
- -    THE FUND'S TOTAL RETURN, LIKE STOCK PRICES GENERALLY, WILL FLUCTUATE WITHIN
     A WIDE  RANGE,  SO AN  INVESTOR  COULD  LOSE  MONEY OVER SHORT OR EVEN LONG
     PERIODS.  Stock  markets  tend to move in  cycles,  with  periods of rising
     prices and periods of falling prices.
- -    The Fund is also subject to investment style risk, which is the chance that
     returns  from  small-capitalization  stocks will trail  returns  from other
     asset classes or the overall stock market.  Small-cap  stocks  historically
     have been more  volatile in price than the  large-cap  stocks that dominate
     the S&P 500 Index, and perform differently than the overall stock market.


PERFORMANCE/RISK INFORMATION
The bar chart and table below  provide an indication of the risk of investing in
the Fund. The bar chart shows the Fund's performance in each calendar year since
inception of the Institutional  class of shares.  The table shows how the Fund's
average annual total returns for one calendar year and since  inception  compare
with  those of the index  that the Fund  seeks to  track.  Keep in mind that the
Fund's past performance does not indicate how it will perform in the future.

- --------------------------------------------------------------------------------
                              ANNUAL TOTAL RETURNS
- --------------------------------------------------------------------------------
                              1998          -2.50%
                              1999          23.33%
- --------------------------------------------------------------------------------
Return figures do not reflect the transaction fee on purchases prior to April 1,
2000.
- --------------------------------------------------------------------------------

     During the period shown in the bar chart, the highest return for a calendar
quarter was 18.63% (quarter ended December 31, 1999) and the lowest return for a
quarter was -20.12% (quarter ended September 30, 1998).

<PAGE>

14


- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                        1 YEAR           SINCE INCEPTION*
- --------------------------------------------------------------------------------
Vanguard Small-Cap Index Fund
  Institutional Shares**                23.33%                12.49%
Russell 2000 Index                      21.26                 11.58
- --------------------------------------------------------------------------------
 *July 7, 1997.
**Return figures do not reflect the transaction fee on purchases prior to
  April 1, 2000.
- --------------------------------------------------------------------------------

FEES AND EXPENSES
The following  table  describes the fees and expenses you may pay if you buy and
hold  Institutional  Shares of the Fund.  The  expenses  shown under Annual Fund
Operating  Expenses  are based upon  those  incurred  in the  fiscal  year ended
December 31, 1999.

      SHAREHOLDER FEES (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                 None
      Transaction Fee on Purchases:                             None*
      Sales Charge (Load) Imposed on Reinvested Dividends:      None
      Redemption Fee:                                           None
      Exchange Fee:                                             None

      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the
      Fund's assets)
      Management Expenses:                                     0.09%
      12b-1 Distribution Fee:                                   None
      Other Expenses:                                          0.03%
       TOTAL ANNUAL FUND OPERATING EXPENSES:                   0.12%

      *The Fund reserves the right to deduct a transaction fee from future
       purchases of shares.


     The following example is intended to help you compare the cost of investing
in the Fund 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.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.


- --------------------------------------------------------------------------------
               1 YEAR      3 YEARS    5 YEARS      10 YEARS
- --------------------------------------------------------------------------------
                $12          $39        $68          $154
- --------------------------------------------------------------------------------


     THIS  EXAMPLE  SHOULD NOT BE  CONSIDERED  TO REPRESENT  ACTUAL  EXPENSES OR
PERFORMANCE  FROM THE PAST OR FOR THE  FUTURE.  ACTUAL  FUTURE  EXPENSES  MAY BE
HIGHER OR LOWER THAN THOSE SHOWN.
<PAGE>

                                                                              15


- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION

DIVIDENDS AND CAPITAL GAINS                    NEWSPAPER ABBREVIATION
Distributed annually in December               SmCapIst

INVESTMENT ADVISER                             VANGUARD FUND NUMBER
The Vanguard Group, Valley Forge, Pa.,         857
since inception
                                               CUSIP NUMBER
INCEPTION DATE                                 922908876
July 7, 1997
                                               TICKER SYMBOL
NET ASSETS (ALL SHARE CLASSES) AS OF           VSCIX
DECEMBER 31, 1999
$4.0 billion
- --------------------------------------------------------------------------------

<PAGE>

16

FUND PROFILE--VANGUARD(R) VALUE INDEX FUND INSTITUTIONAL SHARES

The  following  profile  summarizes  key  features of Vanguard  Value Index Fund
Institutional Shares.

INVESTMENT OBJECTIVE
The Fund seeks to match the  performance of a benchmark  index that measures the
investment return of large-capitalization value stocks.

INVESTMENT STRATEGIES
The Fund employs a passive management strategy designed to track the performance
of the Standard & Poor's  500/BARRA Value Index,  which includes those stocks of
the S&P 500 Index with lower than average price/book ratios. The Fund invests in
the stocks that comprise the Index.

PRIMARY RISKS
- -    THE FUND'S TOTAL RETURN, LIKE STOCK PRICES GENERALLY, WILL FLUCTUATE WITHIN
     A WIDE  RANGE,  SO AN  INVESTOR  COULD  LOSE  MONEY OVER SHORT OR EVEN LONG
     PERIODS.  Stock  markets  tend to move in  cycles,  with  periods of rising
     prices and periods of falling prices.
- -    The Fund is also subject to investment style risk, which is the chance that
     returns  from  large-capitalization  value  stocks will trail  returns from
     other asset classes or the overall  stock  market.  Value stocks tend to go
     through cycles of doing better--or worse--than the stock market in general.
     These periods have, in the past, lasted for as long as several years.

PERFORMANCE/RISK INFORMATION
The bar chart and table below  provide an indication of the risk of investing in
the Fund.  The bar chart shows the Fund's  performance  in the one full calendar
year since inception of the Institutional  class of shares.  The table shows how
the  Fund's  average  annual  total  returns  for one  calendar  year and  since
inception  compare with those of the index that the Fund seeks to track. Keep in
mind that the Fund's past  performance  does not indicate how it will perform in
the future.


- --------------------------------------------------------------------------------
                              ANNUAL TOTAL RETURN
- --------------------------------------------------------------------------------
                              1999         12.67%
- --------------------------------------------------------------------------------

     During the period shown in the bar chart, the highest return for a calendar
quarter was 10.78%  (quarter  ended June 30,  1999) and the lowest  return for a
quarter was -9.22% (quarter ended September 30, 1999).

<PAGE>

                                                                              17

- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                                  1 YEAR       SINCE INCEPTION*
- --------------------------------------------------------------------------------
Vanguard Value Index Fund Institutional Shares    12.67%             8.79%
S&P 500/BARRA Value Index                         12.72              8.78
- --------------------------------------------------------------------------------
*July 2, 1998.
- --------------------------------------------------------------------------------

FEES AND EXPENSES
The following  table  describes the fees and expenses you may pay if you buy and
hold  Institutional  Shares of the Fund.  The  expenses  shown under Annual Fund
Operating  Expenses  are based upon  those  incurred  in the  fiscal  year ended
December 31, 1999.

      SHAREHOLDER FEES (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                 None
      Transaction Fee on Purchases:                             None*
      Sales Charge (Load) Imposed on Reinvested Dividends:      None
      Redemption Fee:                                           None
      Exchange Fee:                                             None

      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the
      Fund's assets)
      Management Expenses:                                     0.10%
      12b-1 Distribution Fee:                                   None
      Other Expenses:                                          0.02%
       TOTAL ANNUAL FUND OPERATING EXPENSES:                   0.12%

      *The Fund reserves the right to deduct a transaction fee from future
       purchases of shares.


     The following example is intended to help you compare the cost of investing
in the Fund 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.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.


- --------------------------------------------------------------------------------
                  1 YEAR      3 YEARS    5 YEARS      10 YEARS
- --------------------------------------------------------------------------------
                   $12          $39        $68          $154
- --------------------------------------------------------------------------------


     THIS  EXAMPLE  SHOULD NOT BE  CONSIDERED  TO REPRESENT  ACTUAL  EXPENSES OR
PERFORMANCE  FROM THE PAST OR FOR THE  FUTURE.  ACTUAL  FUTURE  EXPENSES  MAY BE
HIGHER OR LOWER THAN THOSE SHOWN.
<PAGE>

18


- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION

DIVIDENDS AND CAPITAL GAINS                        NEWSPAPER ABBREVIATION
Dividends are distributed quarterly in March,      ValueIst
June, September, and December; capital gains, if
any, are distributed annually in December          VANGUARD FUND NUMBER
                                                   867
INVESTMENT ADVISER
The Vanguard Group, Valley Forge, Pa.,             CUSIP NUMBER
since inception                                    922908850

INCEPTION DATE                                     TICKER SYMBOL
July 2, 1998                                       VIVIX

NET ASSETS (ALL SHARE CLASSES) AS OF
DECEMBER 31, 1999
$3.8 billion
- --------------------------------------------------------------------------------

<PAGE>

                                                                              19

FUND PROFILE--VANGUARD(R) SMALL-CAP VALUE INDEX FUND INSTITUTIONAL SHARES

The following profile  summarizes key features of Vanguard Small-Cap Value Index
Fund Institutional Shares.

INVESTMENT OBJECTIVE
The Fund seeks to match the  performance of a benchmark  index that measures the
investment return of small-capitalization value stocks.

INVESTMENT STRATEGIES
The Fund employs a passive management strategy designed to track the performance
of the Standard & Poor's SmallCap  600/BARRA  Value Index,  which includes those
stocks of the S&P SmallCap 600 Index with lower than average  price/book ratios.
The Fund invests in the stocks that comprise the Index.

PRIMARY RISKS
- -    THE FUND'S TOTAL RETURN, LIKE STOCK PRICES GENERALLY, WILL FLUCTUATE WITHIN
     A WIDE  RANGE,  SO AN  INVESTOR  COULD  LOSE  MONEY OVER SHORT OR EVEN LONG
     PERIODS.  Stock  markets  tend to move in  cycles,  with  periods of rising
     prices and periods of falling prices.
- -    The Fund is also subject to investment style risk, which is the chance that
     returns  from  small-capitalization  value  stocks will trail  returns from
     other asset classes or the overall  stock  market.  Value stocks tend to go
     through cycles of doing better--or worse--than the stock market in general.
     In addition, small-cap stocks historically have been more volatile in price
     than the  large-cap  stocks that  dominate  the S&P 500 Index,  and perform
     differently than the overall stock market.

PERFORMANCE/RISK INFORMATION

The bar chart and table below  provide an indication of the risk of investing in
the Fund. Because  calendar-year  performance  information is not yet available,
the information presented in the bar chart and table reflects the performance of
the Fund's Investor  Shares (which are offered  through a separate  prospectus).
Performance  information  for the  Institutional  Shares would be  substantially
similar,  since both share classes  represent the same  portfolio of securities;
their  returns  differ only to the extent  that the  expenses of the two classes
differ.
     The bar chart shows the  performance of the Fund's  Investor  Shares in the
one full  calendar  year since  inception  of the Fund.  The table shows how the
Fund's  average  annual total returns for one year and since  inception (for the
Fund's  Investor  Shares) compare with those of the index that the Fund seeks to
track.  Keep in mind that the Fund's past  performance  does not indicate how it
will perform in the future.

<PAGE>

20


- --------------------------------------------------------------------------------
                              ANNUAL TOTAL RETURN
- --------------------------------------------------------------------------------
                              1999          3.35%
- --------------------------------------------------------------------------------
The return  figure  does not  reflect  the  account  maintenance  fee imposed on
accounts  with  balances  of  less  than  $10,000  for  Investor  Shares  or the
transaction fee on purchases.
- --------------------------------------------------------------------------------

     During the period shown in the bar chart, the highest return for a calendar
quarter was 20.08%  (quarter  ended June 30,  1999) and the lowest  return for a
quarter was -9.50% (quarter ended March 31, 1999).

- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------

                                             1 YEAR            SINCE INCEPTION*
- --------------------------------------------------------------------------------
Vanguard Small-Cap Value Index Fund**         2.83%                 -6.31%
S&P SmallCap 600/BARRA Value Index            3.03                  -6.73
- --------------------------------------------------------------------------------
 *May 21, 1998.
**Return figures reflect the transaction fee of 0.50% on purchases, but do not
  reflect the account maintenance fee imposed on accounts with balances of less
  than $10,000 for Investor Shares.
- --------------------------------------------------------------------------------

FEES AND EXPENSES
The following  table  describes the fees and expenses you may pay if you buy and
hold  Institutional  Shares of the Fund.  The  expenses  shown under Annual Fund
Operating  Expenses  are based upon  those  incurred  in the  fiscal  year ended
December 31, 1999.

      SHAREHOLDER FEES (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                 None
      Transaction Fee on Purchases:                            0.50%*
      Sales Charge (Load) Imposed on Reinvested Dividends:      None
      Redemption Fee:                                           None
      Exchange Fee:                                             None

      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the
      Fund's assets)
      Management Expenses:                                     0.10%
      12b-1 Distribution Fee:                                   None
      Other Expenses:                                          0.03%
       TOTAL ANNUAL FUND OPERATING EXPENSES:                   0.13%

      *The  transaction fee is deducted from all purchases (including exchanges
       from other Vanguard funds), but not from reinvested dividends or capital
       gains.

<PAGE>

                                                                              21

     The following example is intended to help you compare the cost of investing
in the Fund 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.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.


- --------------------------------------------------------------------------------
                    1 YEAR      3 YEARS    5 YEARS      10 YEARS
- --------------------------------------------------------------------------------
                     $63          $92        $123         $216
- --------------------------------------------------------------------------------


     THIS  EXAMPLE  SHOULD NOT BE  CONSIDERED  TO REPRESENT  ACTUAL  EXPENSES OR
PERFORMANCE  FROM THE PAST OR FOR THE  FUTURE.  ACTUAL  FUTURE  EXPENSES  MAY BE
HIGHER OR LOWER THAN THOSE SHOWN.


- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION

DIVIDENDS AND CAPITAL GAINS                    NEWSPAPER ABBREVIATION
Distributed annually in December               SmValIst

INVESTMENT ADVISER                             VANGUARD FUND NUMBER
The Vanguard Group, Valley Forge, Pa.,         865
since inception
                                               CUSIP NUMBER
INCEPTION DATE                                 922908785
December 7, 1999

NET ASSETS (ALL SHARE CLASSES) AS OF
DECEMBER 31, 1999
$214 million
- --------------------------------------------------------------------------------

<PAGE>

22

FUND PROFILE--VANGUARD(R) GROWTH INDEX FUND INSTITUTIONAL SHARES

The  following  profile  summarizes  key features of Vanguard  Growth Index Fund
Institutional Shares.

INVESTMENT OBJECTIVE
The Fund seeks to match the  performance of a benchmark  index that measures the
investment return of large-capitalization growth stocks.

INVESTMENT STRATEGIES
The Fund employs a passive management strategy designed to track the performance
of the Standard & Poor's 500/BARRA Growth Index,  which includes those stocks of
the S&P 500 Index with higher than average  price/book  ratios. The Fund invests
in the stocks that comprise the Index.

PRIMARY RISKS
- -    THE FUND'S TOTAL RETURN, LIKE STOCK PRICES GENERALLY, WILL FLUCTUATE WITHIN
     A WIDE  RANGE,  SO AN  INVESTOR  COULD  LOSE  MONEY OVER SHORT OR EVEN LONG
     PERIODS.  Stock  markets  tend to move in  cycles,  with  periods of rising
     prices and periods of falling prices.
- -    The Fund is also subject to investment style risk, which is the chance that
     returns from  large-capitalization  growth  stocks will trail  returns from
     other asset classes or the overall  stock market.  Growth stocks tend to go
     through cycles of doing better--or worse--than the stock market in general.
     These periods have, in the past, lasted for as long as several years.

PERFORMANCE/RISK INFORMATION
The bar chart and table below  provide an indication of the risk of investing in
the Fund.  The bar chart shows the Fund's  performance  in the one full calendar
year since inception of the Institutional  class of shares.  The table shows how
the  Fund's  average  annual  total  returns  for one  calendar  year and  since
inception  compare with those of the index that the Fund seeks to track. Keep in
mind that the Fund's past  performance  does not indicate how it will perform in
the future.


- --------------------------------------------------------------------------------
                              ANNUAL TOTAL RETURN
- --------------------------------------------------------------------------------
                              1999         28.91%
- --------------------------------------------------------------------------------

<PAGE>

                                                                              23


     During the period shown in the bar chart, the highest return for a calendar
quarter was 20.21% (quarter ended December 31, 1999) and the lowest return for a
quarter was -3.52% (quarter ended September 30, 1999).

- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                                  1 YEAR      SINCE INCEPTION*
- --------------------------------------------------------------------------------
Vanguard Growth Index Fund Institutional Shares   28.91%           31.15%
S&P 500/BARRA Growth Index                        28.25            30.61
- --------------------------------------------------------------------------------
*May 14, 1998.
- --------------------------------------------------------------------------------

FEES AND EXPENSES
The following  table  describes the fees and expenses you may pay if you buy and
hold  Institutional  Shares of the Fund.  The  expenses  shown under Annual Fund
Operating  Expenses  are based upon  those  incurred  in the  fiscal  year ended
December 31, 1999.

      SHAREHOLDER FEES (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                 None
      Transaction Fee on Purchases:                             None*
      Sales Charge (Load) Imposed on Reinvested Dividends:      None
      Redemption Fee:                                           None
      Exchange Fee:                                             None

      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the
      Fund's assets)
      Management Expenses:                                     0.10%
      12b-1 Distribution Fee:                                   None
      Other Expenses:                                          0.02%
       TOTAL ANNUAL FUND OPERATING EXPENSES:                   0.12%

      *The Fund reserves the right to deduct a transaction fee from future
       purchases of shares.


     The following example is intended to help you compare the cost of investing
in the Fund 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.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.


- --------------------------------------------------------------------------------
                  1 YEAR      3 YEARS    5 YEARS      10 YEARS
- --------------------------------------------------------------------------------
                   $12          $39        $68          $154
- --------------------------------------------------------------------------------


     THIS  EXAMPLE  SHOULD NOT BE  CONSIDERED  TO REPRESENT  ACTUAL  EXPENSES OR
PERFORMANCE  FROM THE PAST OR FOR THE  FUTURE.  ACTUAL  FUTURE  EXPENSES  MAY BE
HIGHER OR LOWER THAN THOSE SHOWN.
<PAGE>


- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION

DIVIDENDS AND CAPITAL GAINS                        NEWSPAPER ABBREVIATION
Dividends are distributed quarterly in March,      GrowthIst
June, September, and December; capital gains, if
any, are distributed annually in December          VANGUARD FUND NUMBER
                                                   868
INVESTMENT ADVISER
The Vanguard Group, Valley Forge, Pa.,             CUSIP NUMBER
since inception                                    922908868

INCEPTION DATE                                     TICKER SYMBOL
May 14, 1998                                       VIGIX

NET ASSETS (ALL SHARE CLASSES) AS OF
DECEMBER 31, 1999
$15.7 billion
- --------------------------------------------------------------------------------

<PAGE>

                                                                              25

FUND PROFILE--VANGUARD(R) SMALL-CAP GROWTH INDEX FUND INSTITUTIONAL SHARES

The following profile summarizes key features of Vanguard Small-Cap Growth Index
Fund Institutional Shares.

INVESTMENT OBJECTIVE
The Fund seeks to match the  performance of a benchmark  index that measures the
investment return of small-capitalization growth stocks.

INVESTMENT STRATEGIES
The Fund employs a passive management strategy designed to track the performance
of the Standard & Poor's SmallCap  600/BARRA Growth Index,  which includes those
stocks of the S&P SmallCap 600 Index with higher than average price/book ratios.
The Fund invests in the stocks that comprise the Index.

PRIMARY RISKS
- -    THE FUND'S TOTAL RETURN, LIKE STOCK PRICES GENERALLY, WILL FLUCTUATE WITHIN
     A WIDE  RANGE,  SO AN  INVESTOR  COULD  LOSE  MONEY OVER SHORT OR EVEN LONG
     PERIODS.  Stock  markets  tend to move in  cycles,  with  periods of rising
     prices and periods of falling prices.
- -    The Fund is also subject to investment style risk, which is the chance that
     returns from  small-capitalization  growth  stocks will trail  returns from
     other asset classes or the overall  stock market.  Growth stocks tend to go
     through cycles of doing better--or worse--than the stock market in general.
     In addition, small-cap stocks historically have been more volatile in price
     than the  large-cap  stocks that  dominate  the S&P 500 Index,  and perform
     differently than the overall stock market.

PERFORMANCE/RISK INFORMATION

The bar chart and table below  provide an indication of the risk of investing in
the Fund. Because  calendar-year  performance  information is not yet available,
the information presented in the bar chart and table reflects the performance of
the Fund's Investor  Shares (which are offered  through a separate  prospectus).
Performance  information  for the  Institutional  Shares would be  substantially
similar,  since both share classes  represent the same  portfolio of securities;
their  returns  differ only to the extent  that the  expenses of the two classes
differ.
     The bar chart shows the  performance of the Fund's  Investor  Shares in the
one full  calendar  year since  inception  of the Fund.  The table shows how the
Fund's  average  annual total returns for one year and since  inception (for the
Fund's  Investor  Shares) compare with those of the index that the Fund seeks to
track.  Keep in mind that the Fund's past  performance  does not indicate how it
will perform in the future.

<PAGE>

26


- --------------------------------------------------------------------------------
                              ANNUAL TOTAL RETURN
- --------------------------------------------------------------------------------
                              1999         19.80%
- --------------------------------------------------------------------------------
The return  figure  does not  reflect  the  account  maintenance  fee imposed on
accounts  with  balances  of  less  than  $10,000  for  Investor  Shares  or the
transaction fee on purchases.
- --------------------------------------------------------------------------------

     During the period shown in the bar chart, the highest return for a calendar
quarter was 20.69% (quarter ended December 31, 1999) and the lowest return for a
quarter was -8.29% (quarter ended March 31, 1999).

- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                             1 YEAR            SINCE INCEPTION*
- --------------------------------------------------------------------------------
Vanguard Small-Cap Growth Index Fund**       19.20%                 8.17%
S&P SmallCap 600/BARRA Growth Index          19.57                  8.24
- --------------------------------------------------------------------------------
 *May 21, 1998.
**Return figures reflect the transaction fee of 0.50% on purchases, but do not
  reflect the account maintenance fee imposed on accounts with balances of less
  than $10,000 for Investor Shares.
- --------------------------------------------------------------------------------

FEES AND EXPENSES
The following  table  describes the fees and expenses you may pay if you buy and
hold  Institutional  Shares of the Fund.  The  expenses  shown under Annual Fund
Operating  Expenses  are based upon  those  incurred  in the  fiscal  year ended
December 31, 1999.

      SHAREHOLDER FEES (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                 None
      Transaction Fee on Purchases:                            0.50%*
      Sales Charge (Load) Imposed on Reinvested Dividends:      None
      Redemption Fee:                                           None
      Exchange Fee:                                             None

      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the
      Fund's assets)
      Management Expenses:                                     0.10%
      12b-1 Distribution Fee:                                   None
      Other Expenses:                                          0.03%
       TOTAL ANNUAL FUND OPERATING EXPENSES:                   0.13%

      *The transaction fee is deducted from all purchases (including exchanges
       from other Vanguard funds), but not from reinvested dividends or capital
       gains.

<PAGE>

                                                                              27

     The following example is intended to help you compare the cost of investing
in the Fund 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.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.


- --------------------------------------------------------------------------------
                   1 YEAR      3 YEARS    5 YEARS      10 YEARS
- --------------------------------------------------------------------------------
                     $63         $92       $123          $216
- --------------------------------------------------------------------------------


     THIS  EXAMPLE  SHOULD NOT BE  CONSIDERED  TO REPRESENT  ACTUAL  EXPENSES OR
PERFORMANCE  FROM THE PAST OR FOR THE  FUTURE.  ACTUAL  FUTURE  EXPENSES  MAY BE
HIGHER OR LOWER THAN THOSE SHOWN.


- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION
DIVIDENDS AND CAPITAL GAINS                    NEWSPAPER ABBREVIATION
Distributed annually in December               SmGthIst

INVESTMENT ADVISER                             VANGUARD FUND NUMBER
The Vanguard Group, Valley Forge, Pa.,         866
since inception
                                               CUSIP NUMBER
INCEPTION DATE                                 922908819
May 21, 1998

NET ASSETS AS OF DECEMBER 31, 1999
$167 million
- --------------------------------------------------------------------------------

<PAGE>

28

MORE ON THE FUNDS

The   following   sections   discuss  other   important   features  of  Vanguard
Institutional Index Fund and the Vanguard U.S. Stock Index Funds.

INDEXING METHODS
In seeking to track a particular index, a fund generally uses one of two methods
to select stocks.
     Some index funds hold each stock found in their target indexes in about the
same  proportions  as represented  in the indexes  themselves.  This is called a
"replication"  method.  For example,  if 5% of the S&P 500 Index were made up of
the  stock of a  specific  company,  a fund  tracking  that  index  (such as the
Institutional  Index Fund) would invest about 5% of its assets in that  company.
The Institutional Index Fund and the Mid-Cap,  Value,  Small-Cap Value,  Growth,
and Small-Cap Growth Index Funds employ this method of indexing.

     Because it would be very  expensive  to buy and sell all of the stocks held
in certain  indexes (the  Wilshire 5000 Index,  for example,  included more than
7,000 stocks as of December 31, 1999),  many funds tracking these larger indexes
use a "sampling" technique.  Using a sophisticated computer program, these funds
invest in a  representative  sample of stocks from their  target index that will
resemble the full index in terms of industry weightings,  market capitalization,
price/earnings ratio, dividend yield, and other  characteristics.  For instance,
if 10% of the  Wilshire  5000 Index were made up of  utility  stocks,  the Total
Stock Market  Index Fund would  invest about 10% of its assets in some--but  not
all--of those utility  stocks.  The particular  utility  stocks  selected by the
Fund, as a group, would have investment  characteristics similar to those of the
utility  stocks in the Index.  The Total  Stock  Market,  Extended  Market,  and
Small-Cap Index Funds employ this method of indexing.
     The  following  table shows the number of stocks held by each of the Funds,
and the number of stocks in each Fund's target index, as of December 31, 1999.

- --------------------------------------------------------------------------------
                             NUMBER OF                NUMBER OF STOCKS
FUND                        STOCKS HELD               IN TARGET INDEX
- --------------------------------------------------------------------------------
Institutional Index           3,375                       7,093
Total Stock Market              507                         500
Extended Market               2,843                       6,605
Mid-Cap                         402                         400
Small-Cap                     1,768                       1,857
Value                           398                         394
Small-Cap Value                 406                         403
Growth                          110                         106
Small-Cap Growth                198                         197
- --------------------------------------------------------------------------------

<PAGE>

                                                                              29


- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                         GROWTH FUNDS AND VALUE FUNDS
Growth  investing  and value  investing  are two styles  employed  by stock fund
managers.   Growth  funds  generally   focus  on  companies   believed  to  have
above-average  potential  for growth in revenue  and  earnings.  Reflecting  the
market's high  expectations for superior growth,  such stocks typically have low
dividend  yields  and  above-average  prices in  relation  to such  measures  as
revenue,  earnings,  and book value.  Value funds generally  emphasize stocks of
companies  from which the market does not expect  strong  growth.  The prices of
value stocks  typically are  below-average  in  comparison  with such factors as
earnings and book value, and these stocks typically have above-average  dividend
yields.  Growth and value stocks have, in the past,  produced similar  long-term
returns,  though each  category has periods when it  outperforms  the other.  In
general,  growth funds appeal to investors  who will accept more  volatility  in
hopes of a greater  increase  in share  price.  Growth  funds also may appeal to
investors with taxable accounts who want a higher  proportion of returns to come
as capital gains (which may be taxed at lower rates than dividend income). Value
funds, by contrast,  are appropriate for investors who want some dividend income
and the  potential  for capital  gains,  but are less  tolerant  of  share-price
fluctuations.
- --------------------------------------------------------------------------------

ADDITIONAL RISK INFORMATION

[FLAG] EACH FUND IS  SUBJECT  TO MARKET  RISK,  WHICH IS THE  CHANCE  THAT STOCK
     PRICES OVERALL WILL DECLINE OVER SHORT OR EVEN LONG PERIODS.  STOCK MARKETS
     TEND TO MOVE IN CYCLES,  WITH PERIODS OF RISING STOCK PRICES AND PERIODS OF
     FALLING STOCK PRICES.


     To illustrate the volatility of stock prices, the following table shows the
best,  worst,  and average total returns for the U.S.  stock market over various
periods as measured by the S&P 500 Index, which--in addition to being the target
index for  Vanguard 500 Index  Fund--is a widely used  barometer of stock market
activity.  (Total  returns  consist of  dividend  income  plus  change in market
price.)  Note that the  returns  shown do not  include  the costs of buying  and
selling stocks or other expenses that a real-world  investment  portfolio  would
incur.  Note, also, that the gap between best and worst tends to narrow over the
long term.

- --------------------------------------------------------------------------------
                      U.S. STOCK MARKET RETURNS (1926-1999)
- --------------------------------------------------------------------------------
                    1 YEAR      5 YEARS        10 YEARS       20 YEARS
- --------------------------------------------------------------------------------
Best                 54.2%       28.6%           19.9%          17.9%
Worst               -43.1       -12.4            -0.9            3.1
Average              13.2        11.0            11.1           11.1
- --------------------------------------------------------------------------------


     The table  covers all of the 1-, 5-,  10-,  and 20-year  periods  from 1926
through 1999. You can see, for example,  that while the average return on common
stocks for all of the 5-year periods was 11.0%,  returns for  individual  5-year
periods  ranged from a -12.4%  average  (from 1928 through  1932) to 28.6% (from
1995 through 1999).  These average  returns  reflect past  performance on common
stocks;  you should not regard  them as an  indication  of future  returns  from
either the stock market as a whole or any Fund in particular.

<PAGE>

30

     Even  indexes  that  are  subsets  of the  S&P 500  Index--such  as the S&P
500/BARRA Value Index and the S&P 500/BARRA Growth Index (the target indexes for
the Value and  Growth  Index  Funds)--will  not  perform  in the same way as the
broader S&P 500 Index.  Historically,  stocks of the S&P  500/BARRA  Value Index
have been less  volatile  than the stocks  found in the  broader  S&P 500 Index;
stocks of the S&P 500/BARRA  Growth  Index,  on the other hand,  have  displayed
somewhat greater short-term volatility than the S&P 500 Index's stocks. However,
both value and growth  stocks have the  potential  at times to be more  volatile
than the broader market.


[FLAG] THE FUNDS ARE ALSO SUBJECT, IN VARYING DEGREES, TO INVESTMENT STYLE RISK,
     WHICH IS THE  CHANCE  THAT  RETURNS  FROM A  SPECIFIC  TYPE OF  STOCK  (FOR
     INSTANCE,  SMALL-CAP OR VALUE) WILL TRAIL  RETURNS FROM OTHER ASSET CLASSES
     OR THE OVERALL STOCK MARKET.  EACH TYPE OF STOCK TENDS TO GO THROUGH CYCLES
     OF DOING  BETTER--OR  WORSE--THAN  COMMON STOCKS IN GENERAL.  THESE PERIODS
     HAVE, IN THE PAST, LASTED FOR AS LONG AS SEVERAL YEARS.

RISK OF NONDIVERSIFICATION
[FLAG] As index funds,  the  Institutional  Index Fund and the U.S.  Stock Index
Funds each hold the largest stocks in their target indexes in approximately  the
same percentages as those stocks are represented in their indexes. When a target
index becomes less diversified,  a fund that tracks that index similarly becomes
less  diversified.  This has happened to the GROWTH INDEX FUND. Due to the rapid
appreciation  of  certain  stocks  in its  target  index,  the  Fund's  top four
holdings,  as of the date of this  prospectus,  represent  more  than 25% of its
total assets.  By tracking its target  index,  the Fund  technically  has become
"nondiversified"  under SEC  standards,  although it continues to hold more than
100 stock positions in a variety of market sectors.  As the market values of the
Fund's  largest  holdings  rise and fall,  there  may be times  when the Fund is
diversified under SEC standards and other times when it is not.  Shareholders in
Vanguard  Growth Index Fund are subject to the risk that the Fund's  performance
could be hurt disproportionately by a decline in the price of just a few stocks.
     In the unlikely  event that the target  index of any of the other  Vanguard
U.S. Stock Index Funds becomes  dominated by just a few companies,  shareholders
in that Fund would similarly be subject to the risk of nondiversification.


- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                   LARGE-CAP, MID-CAP, AND SMALL-CAP STOCKS
Stocks  of  publicly  traded   companies--and   mutual  funds  that  hold  these
stocks--can be classified by the  companies'  market value,  or  capitalization.
Market  capitalization  changes over time, and there is no "official" definition
of the boundaries of large-,  mid-,  and small-cap  stocks.  Vanguard  generally
defines  large-capitalization  (large-cap)  funds as  those  holding  stocks  of
companies  whose  outstanding  shares have a market value exceeding $12 billion;
mid-cap funds as those holding  stocks of companies  with a market value between
$1 billion and $12  billion;  and  small-cap  funds as those  typically  holding
stocks  of  companies  with a market  value of less  than $1  billion.  Vanguard
periodically reassesses these classifications.
- --------------------------------------------------------------------------------
<PAGE>

                                                                              31

TRANSACTION FEES

Some of  Vanguard's  index funds charge a  transaction  fee on purchases of fund
shares to offset the higher costs of trading  certain  securities,  particularly
small-company  stocks.  The  transaction fee ensures that these higher costs are
borne by the investors making the  transactions--and not by shareholders already
in the  fund  who do not  generate  the  costs.  All  transaction  fees are paid
directly into the fund itself  (unlike a sales charge or load that  non-Vanguard
funds may impose to compensate their sales representatives). Without transaction
fees, some index funds would have trouble tracking their target indexes.


COSTS AND MARKET-TIMING

Some  investors  try to profit from a strategy  called  market-timing--switching
money into  investments  when they expect  prices to rise,  and taking money out
when they expect  prices to fall.  As money is shifted in and out, a fund incurs
expenses  for buying and selling  securities.  These costs are borne by all fund
shareholders,  including the long-term  investors who do not generate the costs.
Therefore,  the  Institutional  Index Fund and the U.S.  Stock  Index Funds have
adopted the following policies,  among others, designed to discourage short-term
trading:

- -    Each Fund  reserves  the right to reject  any  purchase  request--including
     exchanges from other  Vanguard  funds--that it regards as disruptive to the
     efficient  management  of the Fund.  A purchase  request  could be rejected
     because  of the  timing  of the  investment  or  because  of a  history  of
     excessive trading by the investor.

- -    Two  of  the  Funds  (Small-Cap  Value  and  Small-Cap   Growth)  charge  a
     transaction  fee on purchases.  The other Funds reserve the right to impose
     such a fee on selected purchases.

- -    There is a limit on the number of times you can exchange  into and out of a
     Fund (see "Redeeming Shares" in the INVESTING WITH VANGUARD section).
- -    Telephone and online exchanges are not permitted for non-IRA accounts.

     THE  VANGUARD  FUNDS DO NOT  PERMIT  MARKET-TIMING.  DO NOT INVEST IN THESE
FUNDS IF YOU ARE A MARKET-TIMER.

TURNOVER RATE
Generally,  a  passively  managed  fund  sells  securities  only to  respond  to
redemption  requests  or to adjust the number of shares held to reflect a change
in the fund's target index.  Turnover rates for large-cap stock index funds tend
to be very low because large-cap indexes,  such as the S&P 500, typically do not
change much from year to year.  Turnover  rates for mid-cap and small-cap  stock
index  funds tend to be higher  (although  still  relatively  low,  compared  to
actively  managed stock funds) because the indexes they track are more likely to
change as a result of mergers,  acquisitions,  business  failures,  or growth of
companies  than a larger-cap  index.  The turnover rate of each Fund for each of
the last five  years (or since  inception  of the  applicable  share  class,  if
shorter) is shown in the FINANCIAL HIGHLIGHTS section of this prospectus.
<PAGE>

32


- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                                 TURNOVER RATE
Before  investing in a mutual fund,  you should review its turnover  rate.  This
gives an  indication  of how  transaction  costs could affect the fund's  future
returns.  In general,  the greater the volume of buying and selling by the fund,
the greater the impact that brokerage  commissions and other  transaction  costs
will have on its return. Also, funds with high turnover rates may be more likely
to generate  capital gains that must be  distributed to  shareholders  as income
subject to taxes.  As of  December  31,  1999,  the  average  turnover  rate for
passively  managed  domestic  equity index funds  investing in common stocks was
approximately 18%; for all domestic stock funds,  the average  turnover rate was
approximately 89%, according to Morningstar, Inc. (A turnover rate of 100% would
occur, for example, if a fund sold and replaced securities valued at 100% of its
net assets within a one-year period.)
- --------------------------------------------------------------------------------


INVESTMENT POLICIES
Each Fund  reserves the right to  substitute a different  index for the index it
currently  tracks if the current index is  discontinued  or for any other reason
determined  in good  faith by the  Fund's  Board  of  Trustees.  In  every  such
instance,  the substitute  index will measure the same general  market  (large-,
mid-, or small-cap, growth, or value) as the current index.
     Each Fund may invest in foreign securities to the extent necessary to carry
out its investment  strategy of holding all, or a representative  sample, of the
stocks that comprise the index it tracks.  It is not expected that any Fund will
invest more than 5% of its assets in foreign securities.
     Although index funds, by their nature, tend to be tax-efficient  investment
vehicles, the Funds generally are managed without regard to tax ramifications.
     To track their target indexes as closely as possible,  the Funds attempt to
remain  fully  invested in stocks.  To help stay fully  invested,  and to reduce
transaction  costs, the Funds may invest,  to a limited extent, in stock futures
and options contracts,  warrants,  convertible securities,  and swap agreements,
which are types of derivatives.
     Losses (or gains) involving futures can sometimes be  substantial--in  part
because a relatively small price movement in a futures contract may result in an
immediate  and  substantial  loss (or gain) for a fund.  Similar risks exist for
warrants  (securities  that permit their owners to purchase a specific number of
stock shares at a predetermined price),  convertible securities (securities that
may be exchanged for another  asset),  and swap  agreements  (contracts in which
each  party  agrees  to make  payments  to the  other  based on the  return of a
specified index or asset).
     For this  reason,  the  Funds  will  not use  futures,  options,  warrants,
convertible  securities,  or swap  agreements  for  speculative  purposes  or as
leveraged  investments  that  magnify  the gains or losses of an  investment.  A
Fund's  obligation  under futures  contracts  will not exceed 20% of that Fund's
total assets.
     The reasons for which a Fund will invest in futures and options are:
- -    To keep cash on hand to meet  shareholder  redemptions or other needs while
     simulating full investment in stocks.
- -    To reduce the Fund's  transaction costs or add value when these instruments
     are favorably priced.
<PAGE>

                                                                              33

THE FUNDS AND VANGUARD

Vanguard U.S.  Stock Index Funds are members of The Vanguard  Group, a family of
more than 35 investment  companies with more than 100 funds holding assets worth
more than $550 billion.* All of the funds that are members of The Vanguard Group
share in the expenses  associated with business  operations,  such as personnel,
office space, equipment, and advertising.

     Vanguard also  provides  marketing  services to the member funds.  Although
shareholders do not pay sales commissions or 12b-1  distribution fees, each fund
pays its allocated share of The Vanguard Group's marketing costs.

*Vanguard Institutional Index Fund is not a member of The Vanguard Group, but is
 administered by Vanguard and pays Vanguard a fee to provide management,
 advisory, marketing, and other services.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                     VANGUARD'S UNIQUE CORPORATE STRUCTURE
The Vanguard Group is truly a MUTUAL mutual fund company. It is owned jointly by
the funds it oversees and thus  indirectly by the  shareholders  in those funds.
Most other mutual funds are operated by for-profit management companies that may
be owned by one person,  by a group of individuals,  or by investors who own the
management  company's stock. By contrast,  Vanguard  provides its services on an
"at-cost"  basis,  and the funds' expense  ratios  reflect only these costs.  No
separate  management  company reaps profits or absorbs losses from operating the
funds.
- --------------------------------------------------------------------------------


INVESTMENT ADVISER

The Vanguard Group (Vanguard), P.O. Box 2600, Valley Forge, PA 19482, founded in
1975,  serves as the Funds' adviser  through its Core  Management  Group.  As of
December  31,  1999,  Vanguard  served as adviser  for about  $371.4  billion in
assets.

     Under the terms of a service and advisory agreement,  Vanguard pays for all
of  the  Institutional   Index  Fund's  expenses  (except  taxes  and  brokerage
commissions).  In turn, the Fund pays Vanguard a monthly management fee based on
an annual  rate of 0.06% of the  average  daily net assets of the  Institutional
Shares and 0.025% of the  average  daily net  assets of the  Institutional  Plus
Shares.  Vanguard  manages the other Funds on an at-cost  basis,  subject to the
control of the Trustees and officers of the Funds.

     For the fiscal  year ended  December  31,  1999,  the  investment  advisory
expenses  for the  Institutional  Share  classes of the U.S.  Stock  Index Funds
represented  an  effective  annual  rate of  approximately  0.01% of each Fund's
average net assets.

     The Funds have  authorized  Vanguard to choose brokers or dealers to handle
the purchase and sale of securities for the Funds, and to get the best available
price and most  favorable  execution  from  these  brokers  with  respect to all
transactions.  The Funds may  direct  Vanguard  to use a  particular  broker for
certain  transactions  in exchange for commission  rebates or research  services
provided to the Funds.
<PAGE>

34

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                              THE FUNDS' ADVISER
The individual responsible for overseeing each Fund's investments is:

GEORGE U.  SAUTER,  Managing  Director of Vanguard and head of  Vanguard's  Core
Management  Group;  has worked in  investment  management  since  1985;  primary
responsibility  for Vanguard's  stock indexing policy and strategy since joining
the company in 1987; A.B.,  Dartmouth  College;  M.B.A.,  University of Chicago.
- --------------------------------------------------------------------------------


DIVIDENDS, CAPITAL GAINS, AND TAXES

FUND DISTRIBUTIONS

Each Fund distributes to shareholders  virtually all of its net income (interest
and dividends,  less  expenses),  as well as any capital gains realized from the
sale  of its  holdings.  Income  dividends  for  the  Institutional  Index  Fund
(Institutional and Institutional Plus Shares) and the Total Stock Market, Value,
and Growth Index Funds generally are distributed in March, June, September,  and
December;  income  dividends  for  the  Extended  Market,  Mid-Cap,   Small-Cap,
Small-Cap  Value,  and Small-Cap Growth Index Funds generally are distributed in
December.  Capital gains distributions generally occur in December. In addition,
the Funds may occasionally be required to make supplemental  dividend or capital
gains  distributions  at some  other  time  during  the  year.  You can  receive
distributions of income dividends or capital gains in cash, or you can have them
automatically reinvested in more shares of the Fund.


BASIC TAX POINTS
Vanguard will send you a statement  each year showing the tax status of all your
distributions.  In addition,  taxable investors should be aware of the following
basic tax points:

- -    Distributions are taxable to you for federal income tax purposes whether or
     not you reinvest these amounts in additional Fund shares.
- -    Distributions   declared  in  December--if  paid  to  you  by  the  end  of
     January--are  taxable  for  federal  income tax  purposes as if received in
     December.

- -    Any dividends and short-term  capital gains that you receive are taxable to
     you as ordinary income for federal income tax purposes.
- -    Any  distributions  of net  long-term  capital  gains are taxable to you as
     long-term capital gains for federal income tax purposes, no matter how long
     you've owned shares in the Fund.
- -    Capital gains  distributions  may vary  considerably from year to year as a
     result of the Funds' normal investment activities and cash flows.
- -    A sale or exchange of Fund shares is a taxable  event.  This means that you
     may have a capital gain to report as income, or a capital loss to report as
     a deduction, when you complete your federal income tax return.

- -    Dividend and capital gains  distributions that you receive, as well as your
     gains or losses from any sale or exchange of Fund shares, may be subject to
     state and local income taxes.

<PAGE>

                                                                              35

GENERAL INFORMATION

BACKUP  WITHHOLDING.   By  law,  Vanguard  must  withhold  31%  of  any  taxable
distributions or redemptions from your account if you do not:
- -    provide us with your correct taxpayer identification number;
- -    certify that the taxpayer identification number is correct; and
- -    confirm that you are not subject to backup withholding.
Similarly,  Vanguard  must withhold from your account if the IRS instructs us to
do so.

FOREIGN  INVESTORS.  The Vanguard funds  generally do not offer their shares for
sale outside of the United States.  Foreign  investors should be aware that U.S.
withholding and estate taxes may apply to any investments in Vanguard funds.
INVALID  ADDRESSES.  If a dividend or capital gains distribution check mailed to
your address of record is returned as undeliverable, Vanguard will automatically
reinvest  all future  distributions  until you  provide us with a valid  mailing
address.
TAX CONSEQUENCES. This prospectus provides general tax information only. If you
are investing through a tax-deferred retirement account, such as an IRA, special
tax rules apply. Please consult your tax adviser for detailed information about
a fund's tax consequences for you.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                                 DISTRIBUTIONS
As a  shareholder,  you are  entitled  to your share of the fund's  income  from
interest and dividends, and gains from the sale of investments. You receive such
earnings as either an income  dividend or a capital gains  distribution.  Income
dividends come from both the dividends that the fund earns from its holdings and
the  interest it receives  from its money market and bond  investments.  Capital
gains are realized  whenever the fund sells securities for higher prices than it
paid for them. These capital gains are either short-term or long-term, depending
on whether the fund held the  securities  for one year or less, or more than one
year.
- --------------------------------------------------------------------------------


SHARE PRICE

Each Fund's share price,  called its net asset value, or NAV, is calculated each
business day after the close of regular  trading on the New York Stock  Exchange
(the NAV is not  calculated  on  holidays  or other  days when the  Exchange  is
closed).  Net asset  value per share is computed by adding up the total value of
the  Fund's  investments  and  other  assets  attributed  to each  share  class,
subtracting any of its liabilities  (debts)  attributed to each share class, and
then dividing by the number of Fund shares outstanding for each share class:

                          TOTAL ASSETS - LIABILITIES
     NET ASSET VALUE = -------------------------------
                         NUMBER OF SHARES OUTSTANDING

     Knowing the daily net asset value is useful to you as a shareholder because
it indicates the current value of your investment. The Fund's NAV, multiplied by
the  number of  shares  you own,  gives you the  dollar  amount  you would  have
received had you sold all of your shares back to the Fund that day.
     A NOTE ON  PRICING:  A Fund's  investments  will be priced at their  market
value when market  quotations are readily  available.  When these quotations are
not  readily  available,  invest-
<PAGE>

36

ments will be priced at their fair value,  calculated  according  to  procedures
adopted by the Funds' Board of Trustees.
     Each Fund's  share price can be found daily in the mutual fund  listings of
most major  newspapers  under the  heading  "Vanguard  Index  Funds."  Different
newspapers  use different  abbreviations  for each Fund, but the most common are
INSTIDX, INSTPLUS,  TOTSTIST,  EXTNDIST, MIDCPIST, SMCAPIST, VALUEIST, SMVALIST,
GRWTHIST, and SMGTHIST.


FINANCIAL HIGHLIGHTS

The following  financial  highlights  tables are intended to help you understand
each Fund's financial  performance for the past five years or since  inception*,
and certain  information  reflects  financial results for a single Fund share in
each case.  The total returns in each table  represent the rate that an investor
would have earned or lost each  period on an  investment  in the Fund  (assuming
reinvestment of all dividend and capital gains distributions).  This information
has been derived from the financial statements audited by PricewaterhouseCoopers
LLP,  independent  accountants,  whose  report--along  with the Funds' financial
statements--is  included in the  Institutional  Index Fund's and the U.S.  Stock
Index Funds' most recent annual reports to shareholders. You may have the annual
reports for the Institutional  Index Fund and the U.S. Stock Index Funds sent to
you without charge by contacting Vanguard.

*Because the Small-Cap Growth Index  Fund has  not yet issued  any Institutional
 Shares, a financial highlights table is not included for this Fund.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                  HOW TO READ THE FINANCIAL HIGHLIGHTS TABLE

This explanation uses the Institutional  Index Fund  Institutional  Shares as an
example.  The Fund began  fiscal 1999 with a net asset value  (price) of $112.85
per share.  During the year,  the Fund earned  $1.501 per share from  investment
income  (interest and dividends) and $22.143 per share from investments that had
appreciated  in value or that were sold for higher prices than the Fund paid for
them.

Shareholders received $2.474 per share in the form of dividend and capital gains
distributions.  A portion of each year's  distributions  may come from the prior
year's income or capital gains.

The  earnings  ($23.644 per share)  minus the  distributions  ($2.474 per share)
resulted  in a share  price  of  $134.02  at the end of the  year.  This  was an
increase  of $21.17  per share  (from  $112.85 at the  beginning  of the year to
$134.02  at  the  end  of  the  year).  For a  shareholder  who  reinvested  the
distributions in the purchase of more shares, the total return from the Fund was
21.17% for the year.

As of December 31, 1999, the Fund had $28.9 billion in net assets. For the year,
its expense ratio was 0.06% ($0.60 per $1,000 of net assets); and net investment
income  amounted  to 1.25%  of its  average  net  assets.  It sold and  replaced
securities valued at 14% of its net assets.
- --------------------------------------------------------------------------------

<PAGE>

                                                                              37

<TABLE>
<CAPTION>
- ---------------------------------------------------------------------------------------------------------
                                                              VANGUARD INSTITUTIONAL INDEX FUND
                                                                     INSTITUTIONAL SHARES
                                                                    YEAR ENDED DECEMBER 31,
                                      -------------------------------------------------------------------
                                             1999          1998          1997          1996         1995
- ---------------------------------------------------------------------------------------------------------
<S>                                       <C>            <C>           <C>           <C>          <C>
NET ASSET VALUE, BEGINNING OF YEAR        $112.85        $89.56        $68.86        $57.93       $43.22
- ---------------------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
 Net Investment Income                      1.501         1.429         1.391          1.38         1.28
 Net Realized and Unrealized Gain (Loss)
   on Investments                          22.143        24.177        21.415         11.90        14.86
                                      -------------------------------------------------------------------
   Total from Investment Operations        23.644        25.606        22.806         13.28        16.14
                                      -------------------------------------------------------------------
DISTRIBUTIONS
 Dividends from Net Investment Income      (1.514)       (1.416)       (1.391)        (1.36)       (1.27)
 Distributions from Realized Capital Gains  (.960)        (.900)        (.715)         (.99)        (.16)
                                      -------------------------------------------------------------------
   Total Distributions                     (2.474)       (2.316)       (2.106)        (2.35)       (1.43)
- ---------------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF YEAR              $134.02       $112.85        $89.56        $68.86       $57.93
=========================================================================================================
TOTAL RETURN                               21.17%        28.79%        33.36%        23.06%       37.60%
=========================================================================================================
RATIOS/SUPPLEMENTAL DATA
 Net Assets, End of Year (Millions)       $28,918       $22,338       $15,348       $11,426       $6,674
 Ratio of Total Expenses to Average
   Net Assets                               0.06%         0.06%         0.06%         0.06%        0.06%
 Ratio of Net Investment Income to Average
   Net Assets                               1.25%         1.46%         1.77%         2.18%        2.49%
 Turnover Rate*                               14%           11%            7%            9%           4%
=========================================================================================================
*Turnover rates excluding in-kind redemptions were 3%, 7%, 6%, 9%, and 4%, respectively.
</TABLE>


<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------
                                                                VANGUARD INSTITUTIONAL INDEX FUND
                                                                        INSTITUTIONAL PLUS SHARES
                                                        YEAR ENDED DEC. 31,
                                                     ---------------------------       JULY 7* TO
                                                          1999        1998          DEC. 31, 1997
- --------------------------------------------------------------------------------------------------
<S>                                                    <C>          <C>                    <C>
NET ASSET VALUE, BEGINNING OF PERIOD                   $112.85      $89.56                 $84.91
- --------------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
 Net Investment Income                                   1.542       1.464                   .681
 Net Realized and Unrealized Gain (Loss) on Investments 22.143      24.177                  5.455
                                                        ------------------------------------------
   Total from Investment Operations                     23.685      25.641                  6.136
                                                        ------------------------------------------
DISTRIBUTIONS
 Dividends from Net Investment Income                   (1.555)     (1.451)                 (.866)
 Distributions from Realized Capital Gains               (.960)      (.900)                 (.620)
                                                        ------------------------------------------
   Total Distributions                                  (2.515)     (2.351)                (1.486)
- --------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                         $134.02     $112.85                 $89.56
==================================================================================================
TOTAL RETURN                                            21.21%      28.83%                  7.29%
==================================================================================================
RATIOS/SUPPLEMENTAL DATA
 Net Assets, End of Period (Millions)                   $6,861      $4,951                 $3,488
 Ratio of Total Expenses to Average Net Assets          0.025%      0.025%               0.025%**
 Ratio of Net Investment Income to Average Net Assets    1.29%       1.49%                1.72%**
 Turnover Rate+                                            14%         11%                     7%
==================================================================================================
 *Inception.
**Annualized.
 +Turnover rates excluding in-kind redemptions were 3%, 7%, and  6%, respectively.
</TABLE>

<PAGE>

38


<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------
                                                           VANGUARD TOTAL STOCK MARKET INDEX FUND
                                                                             INSTITUTIONAL SHARES
                                                        YEAR ENDED DEC. 31,
                                                     ---------------------------       JULY 7* TO
                                                          1999        1998          DEC. 31, 1997
- --------------------------------------------------------------------------------------------------
<S>                                                     <C>         <C>                    <C>
NET ASSET VALUE, BEGINNING OF PERIOD                    $27.42      $22.64                 $21.27
- --------------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
 Net Investment Income                                    .344        .359                   .172
 Net Realized and Unrealized Gain (Loss) on Investments  6.133       4.898                  1.642
                                                       -------------------------------------------
   Total from Investment Operations                      6.477       5.257                  1.814
                                                       -------------------------------------------
DISTRIBUTIONS
 Dividends from Net Investment Income                    (.357)      (.352)                 (.214)
 Distributions from Realized Capital Gains               (.320)      (.125)                 (.230)
                                                       -------------------------------------------
   Total Distributions                                   (.677)      (.477)                 (.444)
- --------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                          $33.22      $27.42                 $22.64
==================================================================================================
TOTAL RETURN                                            23.93%      23.37%                  8.60%
==================================================================================================
RATIOS/SUPPLEMENTAL DATA
 Net Assets, End of Period (Millions)                   $4,006      $2,445                 $1,504
 Ratio of Total Expenses to Average Net Assets           0.10%       0.10%                0.10%**
 Ratio of Net Investment Income to Average Net Assets    1.26%       1.53%                1.70%**
 Turnover Rate+                                             3%          3%                     2%
==================================================================================================
 *Inception.
**Annualized.
</TABLE>


<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------
                                                              VANGUARD EXTENDED MARKET INDEX FUND
                                                                             INSTITUTIONAL SHARES
                                                        YEAR ENDED DEC. 31,
                                                     ---------------------------       JULY 7* TO
                                                          1999       1998           DEC. 31, 1997
- --------------------------------------------------------------------------------------------------
<S>                                                     <C>        <C>                     <C>
NET ASSET VALUE, BEGINNING OF PERIOD                    $30.63     $30.76                  $29.28
- --------------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
 Net Investment Income                                    .363       .427                    .200
 Net Realized and Unrealized Gain (Loss) on Investments 10.101      2.025                   3.191
                                                       -------------------------------------------
   Total from Investment Operations                     10.464      2.452                   3.391
                                                       -------------------------------------------
DISTRIBUTIONS
 Dividends from Net Investment Income                    (.364)     (.412)                  (.371)
 Distributions from Realized Capital Gains              (3.640)    (2.170)                 (1.540)
                                                       -------------------------------------------
   Total Distributions                                  (4.004)    (2.582)                 (1.911)
- --------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                          $37.09     $30.63                  $30.76
==================================================================================================
TOTAL RETURN**                                          36.45%      8.45%                  11.82%
==================================================================================================
RATIOS/SUPPLEMENTAL DATA
 Net Assets, End of Period (Millions)                     $870       $456                    $415
 Ratio of Total Expenses to Average Net Assets           0.10%      0.10%                  0.10%+
 Ratio of Net Investment Income to Average Net Assets    1.18%      1.34%                  1.43%+
 Turnover Rate+                                            26%        27%                     15%
==================================================================================================
 *Inception.
**Total return figures do not reflect transaction fees on purchases (0.25% from October 31, 1997 through
  March 31, 2000; 0.5% from inception through October 31, 1997).
 +Annualized.
</TABLE>

<PAGE>

                                                                              39

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------
                                                                      VANGUARD MID-CAP INDEX FUND
                                                                             INSTITUTIONAL SHARES
                                                                 YEAR ENDED            MAY 20* TO
                                                               DEC. 31,1999         DEC. 31, 1998
- --------------------------------------------------------------------------------------------------
<S>                                                                  <C>                  <C>
NET ASSET VALUE, BEGINNING OF PERIOD                                 $10.79                $10.03
- --------------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
 Net Investment Income                                                 .083                  .055
 Net Realized and Unrealized Gain (Loss) on Investments               1.448                  .814
                                                              ------------------------------------
   Total from Investment Operations                                   1.531                  .869
                                                              ------------------------------------
DISTRIBUTIONS
 Dividends from Net Investment Income                                 (.086)                (.059)
 Distributions from Realized Capital Gains                            (.935)                (.050)
                                                              ------------------------------------
   Total Distributions                                               (1.021)                (.109)
- --------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                                       $11.30                $10.79
==================================================================================================
TOTAL RETURN**                                                       15.41%                 8.61%
==================================================================================================
RATIOS/SUPPLEMENTAL DATA
 Net Assets, End of Period (Millions)                                  $143                   $39
 Ratio of Total Expenses to Average Net Assets                        0.12%                0.12%+
 Ratio of Net Investment Income to Average Net Assets                 1.11%                1.30%+
 Turnover Rate                                                          38%                   44%
==================================================================================================
 *Initial share purchase date. Subscription period for the Fund was April 20, 1998, to May 20, 1998,
  during which time all assets were held in money market instruments. Performance measurement begins
  May 21, 1998.
**Total return figures do not reflect the 0.25% transaction fee on purchases (from inception through
  February 28, 1999).
 +Annualized.
</TABLE>


<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------
                                                                    VANGUARD SMALL-CAP INDEX FUND
                                                                             INSTITUTIONAL SHARES
                                                        YEAR ENDED DEC. 31,
                                                     ---------------------------       JULY 7* TO
                                                         1999        1998           DEC. 31, 1997
- --------------------------------------------------------------------------------------------------
<S>                                                    <C>         <C>                     <C>
NET ASSET VALUE, BEGINNING OF PERIOD                   $21.20      $23.75                  $22.56
- --------------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
 Net Investment Income                                   .295        .336                    .158
 Net Realized and Unrealized Gain (Loss) on Investments 4.491      (1.007)                  2.370
                                                       -------------------------------------------
   Total from Investment Operations                     4.786       (.671)                  2.528
                                                       -------------------------------------------
DISTRIBUTIONS
 Dividends from Net Investment Income                   (.296)      (.329)                  (.288)
 Distributions from Realized Capital Gains             (2.080)     (1.550)                 (1.050)
                                                       -------------------------------------------
   Total Distributions                                 (2.376)     (1.879)                 (1.338)
- --------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                         $23.61      $21.20                  $23.75
==================================================================================================
TOTAL RETURN**                                         23.33%      -2.50%                  11.42%
==================================================================================================
RATIOS/SUPPLEMENTAL DATA
 Net Assets, End of Period (Millions)                    $415        $264                    $137
 Ratio of Total Expenses to Average Net Assets          0.12%       0.12%                  0.12%+
 Ratio of Net Investment Income to Average Net Assets   1.37%       1.53%                  1.52%+
 Turnover Rate                                            42%         35%                     29%
==================================================================================================
 *Inception.
**Total return figures do not reflect the 0.5% transaction fee on purchases (from inception through
  March 31, 2000).
 +Annualized.
</TABLE>

<PAGE>

40


<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------
                                                                        VANGUARD VALUE INDEX FUND
                                                                             INSTITUTIONAL SHARES
                                                                 YEAR ENDED            JULY 2* TO
                                                               DEC. 31,1999         DEC. 31, 1998
- --------------------------------------------------------------------------------------------------
<S>                                                                  <C>                   <C>
NET ASSET VALUE, BEGINNING OF PERIOD                                 $22.51                $23.22
- --------------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
 Net Investment Income                                                 .377                  .196
 Net Realized and Unrealized Gain (Loss) on Investments               2.342                 (.060)
                                                              ------------------------------------
   Total from Investment Operations                                   2.719                  .136
                                                              ------------------------------------
DISTRIBUTIONS
 Dividends from Net Investment Income                                 (.384)                (.236)
 Distributions from Realized Capital Gains                           (1.955)                (.610)
                                                              ------------------------------------
   Total Distributions                                               (2.339)                (.846)
- --------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                                       $22.89                $22.51
==================================================================================================
TOTAL RETURN                                                         12.67%                 0.69%
==================================================================================================
RATIOS/SUPPLEMENTAL DATA
 Net Assets, End of Period (Millions)                                  $460                  $186
 Ratio of Total Expenses to Average Net Assets                        0.12%               0.12%**
 Ratio of Net Investment Income to Average Net Assets                 1.68%               1.90%**
 Turnover Rate                                                          41%                   33%
==================================================================================================
 *Inception.
**Annualized.
</TABLE>


<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------
                                                              VANGUARD SMALL-CAP VALUE INDEX FUND
                                                                             INSTITUTIONAL SHARES
                                                                                       DEC. 7* TO
                                                                                    DEC. 31, 1999
- --------------------------------------------------------------------------------------------------
<S>                                                                                         <C>
NET ASSET VALUE, BEGINNING OF PERIOD                                                        $8.74
- --------------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
 Net Investment Income                                                                       .009
 Net Realized and Unrealized Gain (Loss) on Investments                                      .226
                                                                                    --------------
   Total from Investment Operations                                                          .235
                                                                                    --------------
DISTRIBUTIONS
 Dividends from Net Investment Income                                                       (.070)
 Distributions from Realized Capital Gains                                                  (.455)
                                                                                    --------------
   Total Distributions                                                                      (.525)
- --------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                                                              $8.45
==================================================================================================
TOTAL RETURN**                                                                              2.83%
==================================================================================================
RATIOS/SUPPLEMENTAL DATA
 Net Assets, End of Period (Millions)                                                         $10
 Ratio of Total Expenses to Average Net Assets                                             0.13%+
 Ratio of Net Investment Income to Average Net Assets                                      1.37%+
 Turnover Rate                                                                                80%
==================================================================================================
 *Inception.
**Total return does not reflect the 0.5% transaction fee on purchases.
 +Annualized.
</TABLE>

<PAGE>

                                                                              41


<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------
                                                                       VANGUARD GROWTH INDEX FUND
                                                                             INSTITUTIONAL SHARES
                                                                 YEAR ENDED            MAY 14* TO
                                                               DEC. 31,1999         DEC. 31, 1998
- --------------------------------------------------------------------------------------------------
<S>                                                                  <C>                   <C>
NET ASSET VALUE, BEGINNING OF PERIOD                                 $31.67                $26.49
- --------------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
 Net Investment Income                                                 .249                  .167
 Net Realized and Unrealized Gain (Loss) on Investments               8.821                 5.315
                                                              ------------------------------------
   Total from Investment Operations                                   9.070                 5.482
                                                              ------------------------------------
DISTRIBUTIONS
 Dividends from Net Investment Income                                 (.260)                (.187)
 Distributions from Realized Capital Gains                           (1.040)                (.115)
                                                              ------------------------------------
   Total Distributions                                               (1.300)                (.302)
- --------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                                       $39.44                $31.67
==================================================================================================
TOTAL RETURN                                                         28.91%                20.79%
==================================================================================================
RATIOS/SUPPLEMENTAL DATA
 Net Assets, End of Period (Millions)                                  $452                  $224
 Ratio of Total Expenses to Average Net Assets                        0.12%               0.12%**
 Ratio of Net Investment Income to Average Net Assets                 0.74%               0.97%**
 Turnover Rate                                                          33%                   29%
==================================================================================================
 *Inception.
**Annualized.
</TABLE>



"Standard & Poor's(R),"  "S&P(R)," "S&P 500(R)," "Standard & Poor's 500," "500,"
"S&P MidCap  400," and "S&P  SmallCap  600" are  trademarks  of The  McGraw-Hill
Companies,  Inc.,  and have been licensed for use by Vanguard  U.S.  Stock Index
Funds and The Vanguard  Group.  These mutual funds are not sponsored,  endorsed,
sold,  or  promoted  by  Standard  &  Poor's,  and  Standard  & Poor's  makes no
representation  regarding the advisability of investing in the Funds.  "Wilshire
4500" and "Wilshire  5000" are  registered  trademarks  of Wilshire  Associates.
Frank Russell Company is the owner of the trademarks and copyrights  relating to
the Russell Indexes.
<PAGE>

42

- --------------------------------------------------------------------------------
INVESTING WITH VANGUARD

Are you looking for the most  convenient  way to open or add money to a Vanguard
account? Obtain instant access to fund information?
     Vanguard  can help.  Our goal is to make it easy and pleasant for you to do
business with us.
     The following  sections of the prospectus briefly explain the many services
we offer.  Booklets providing detailed information are available on the services
marked with a [BOOKLET]. Please call us to request copies.
- --------------------------------------------------------------------------------


SERVICES AND ACCOUNT FEATURES

Vanguard  offers many services that make it convenient to buy, sell, or exchange
shares, or to obtain fund or account information.
- --------------------------------------------------------------------------------
TELEPHONE REDEMPTIONS (SALES AND EXCHANGES)
Automatically set up for each Fund unless you notify us otherwise.

Note: Limitations do apply; see page 46.

- --------------------------------------------------------------------------------
VANGUARD(R) AUTOMATIC EXCHANGE SERVICE [BOOKLET]
Automatic  method for  moving a fixed  amount of money  from one  Vanguard  fund
account to another.
- --------------------------------------------------------------------------------
VANGUARD TELE-ACCOUNT(R) 1-800-662-6273 (ON-BOARD) [BOOKLET]
Toll-free  24-hour access to Vanguard fund and account  information--as  well as
some  transactions--by  using any touch-tone phone.  Tele-Account provides total
return,  share price, price change, and yield quotations for all Vanguard funds;
gives your account balances and history (e.g., last transaction, latest dividend
distribution);  and  allows  you to sell or  exchange  shares  to and from  most
Vanguard funds.
- --------------------------------------------------------------------------------
ACCESS VANGUARD(TM) www.vanguard.com [COMPUTER]
You can use your  personal  computer to perform  certain  transactions  for most
Vanguard  funds by accessing our website.  To establish  this service,  you must
register  through our website.  We will then mail you an account access password
that  allows  you  to  process  the  following   financial  and   administrative
transactions online:
- -    Open a new account.*
- -    Buy, sell, or exchange shares of most funds.
- -    Change your name/address.
- -    Add/change   fund   options   (including   dividend   options,    bank
     instructions,  checkwriting, and Vanguard Automatic Exchange Service).
     (Some  restrictions  may  apply.)  Please call your  assigned  Service
     Associate for assistance.

*Only current Vanguard shareholders can open a new account online, by exchanging
 shares from other existing Vanguard accounts.
- --------------------------------------------------------------------------------
SERVICES FOR CLIENTS OF VANGUARD'S INSTITUTIONAL DIVISION: 1-888-809-8102
Vanguard's  Institutional  Division offers a variety of specialized services for
large  institutional   investors,   including  the  ability  to  effect  account
transactions through private electronic networks and third-party recordkeepers.
- --------------------------------------------------------------------------------
<PAGE>

                                                                              43

TYPES OF ACCOUNTS

Individuals and institutions can establish a variety of accounts with Vanguard.
- --------------------------------------------------------------------------------
FOR ONE OR MORE PEOPLE
Open an account in the name of one (individual) or more (joint tenants) people.
- --------------------------------------------------------------------------------
FOR HOLDING PERSONAL TRUST ASSETS [BOOKLET]
Invest assets held in an existing personal trust.
- --------------------------------------------------------------------------------
FOR AN ORGANIZATION [BOOKLET]
Open an account as a corporation,  partnership,  endowment, foundation, or other
entity.
- --------------------------------------------------------------------------------

- --------------------------------------------------------------------------------
A NOTE ON INVESTING WITH VANGUARD THROUGH OTHER FIRMS
You may purchase or sell Fund shares through a financial  intermediary such as a
bank,  broker,  or investment  adviser.  If you invest with Vanguard  through an
intermediary,  please read that firm's program  materials  carefully to learn of
any  special  rules  that may apply.  For  example,  special  terms may apply to
additional service features, fees, or other policies.  Consult your intermediary
to determine when your order will be priced.
- --------------------------------------------------------------------------------


BUYING SHARES

You buy your shares at a Fund's  next-determined  net asset value after Vanguard
receives your request.  As long as your request is received  before the close of
trading on the New York Stock Exchange,  generally 4 p.m. Eastern time, you will
buy your shares at that day's net asset  value.  You may  convert  Institutional
Shares of the Institutional  Index Fund into  Institutional  Plus Shares, or you
may convert  Investor  Shares of any U.S. Stock Index Fund (except the 500 Index
Fund)  into  Institutional  Shares of the same Fund  provided  that you meet the
minimum initial investment requirements for such Shares.

- --------------------------------------------------------------------------------
MINIMUM INVESTMENT TO . . .
open a new account
$10 million.

add to an existing account
$100 by mail or exchange; $1,000 by wire.
- --------------------------------------------------------------------------------
BY WIRE TO OPEN A NEW ACCOUNT OR ADD TO AN EXISTING ACCOUNT [WIRE]
Call your assigned Service Associate to arrange your wire transaction.

Wire to:
FRB ABA 021001088
HSBC Bank USA

For credit to:
Account: 000112046
Vanguard Incoming Wire Account

In favor of:
Vanguard Institutional Index Fund-94
Vanguard Institutional Index Fund Institutional Plus Shares-854
<PAGE>

44

Vanguard Total Stock Market Index Fund Institutional Shares-855
Vanguard Extended Market Index Fund Institutional Shares-856
Vanguard Mid-Cap Index Fund Institutional Shares-864
Vanguard Small-Cap Index Fund Institutional Shares-857
Vanguard Value Index Fund Institutional Shares-867
Vanguard Small-Cap Value Index Fund Institutional Shares-865
Vanguard Growth Index Fund Institutional Shares-868
Vanguard Small-Cap Growth Index Fund Institutional Shares-866
[Account number, or temporary number for a new account]
[Registered account owner(s)]
[Registered address]
- --------------------------------------------------------------------------------
BY MAIL TO . . .[ENVELOPE]
open a new account
Complete and sign the account registration form and enclose your check.

add to an existing account
Mail your check with an  Invest-By-Mail  form  detached  from your  confirmation
statement to the address listed on the form. Please do not alter  Invest-By-Mail
forms, since they are fund- and account-specific.

Make your check payable to: The Vanguard Group-(insert appropriate Fund number;
see below)
Vanguard Institutional Index Fund-94
Vanguard Institutional Index Fund Institutional Plus Shares-854
Vanguard Total Stock Market Index Fund Institutional Shares-855
Vanguard Extended Market Index Fund Institutional Shares-856
Vanguard Mid-Cap Index Fund Institutional Shares-864
Vanguard Small-Cap Index Fund Institutional Shares-857
Vanguard Value Index Fund Institutional Shares-867
Vanguard Small-Cap Value Index Fund Institutional Shares-865
Vanguard Growth Index Fund Institutional Shares-868
Vanguard Small-Cap Growth Index Fund Institutional Shares-866

All  purchases  must be made in U.S.  dollars,  and checks must be drawn on U.S.
banks.


First-class mail to:               Express or Registered mail to:
The Vanguard Group                 The Vanguard Group
P.O. Box 2900                      100 Vanguard Boulevard
Valley Forge, PA 19482-2900        Malvern, PA 19355-2331

- --------------------------------------------------------------------------------
IMPORTANT  NOTE:  To prevent  check fraud,  Vanguard will not accept checks made
payable to third parties.
- --------------------------------------------------------------------------------
BY TELEPHONE TO . . .[TELEPHONE]
open a new account
Call Vanguard  Tele-Account* 24 hours a day--or your assigned Service  Associate
during business  hours--to  exchange from another Vanguard fund account with the
same registration (name, address,  taxpayer  identification  number, and account
type). (Note that some restrictions apply to index fund accounts.)
<PAGE>

                                                                              45

add to an existing account
Call Vanguard  Tele-Account* 24 hours a day--or your assigned Service  Associate
during business  hours--to  exchange from another Vanguard fund account with the
same registration (name, address,  taxpayer  identification  number, and account
type). (Note that some restrictions apply to index fund accounts.)

Vanguard Tele-Account
1-800-662-6273

*You must obtain a Personal  Identification Number (PIN) through Tele-Account at
 least seven days before you request your first exchange.

- --------------------------------------------------------------------------------
IMPORTANT  NOTE:  Once  you  have  initiated  a  telephone   transaction  and  a
confirmation  number has been assigned,  the transaction  cannot be revoked.  We
reserve the right to refuse any purchase request.
- --------------------------------------------------------------------------------
You can redeem  (that is, sell or  exchange)  shares  purchased  by check at any
time.  However,   while  your  redemption  request  will  be  processed  at  the
next-determined  net asset value after it is received,  your redemption proceeds
will not be available  until payment for your  purchase is collected,  which may
take up to ten calendar days.
- --------------------------------------------------------------------------------
A NOTE ON LARGE  PURCHASES
It is important that you call Vanguard  before you invest a large dollar amount.
It is our responsibility to consider the interests of all Fund shareholders, and
so we  reserve  the right to refuse any  purchase  that may  disrupt  the Fund's
operation or performance.
- --------------------------------------------------------------------------------


REDEEMING SHARES

This section  describes how you can redeem--that is, sell or exchange--a  Fund's
shares.

When Selling Shares:
- -    Vanguard sends the redemption proceeds to you or a designated third party.*
- -    You can sell all or part of your Fund shares at any time.


*May require a signature guarantee; see footnote on page 47.


When Exchanging Shares:
- -    The redemption proceeds are used to purchase shares of a different Vanguard
     fund.
- -    You must meet the receiving fund's minimum investment requirements.
- -    Vanguard reserves the right to revise or terminate the exchange  privilege,
     limit the amount of an exchange, or reject an exchange at any time, without
     notice.
- -    In  order  to  exchange  into  an  account  with a  different  registration
     (including a different name, address, or taxpayer  identification  number),
     you must include the guaranteed signatures of all current account owners on
     your written instructions.


In both  cases,  your  transaction  will be based on the Fund's  next-determined
share price, subject to any special rules discussed in this prospectus.

- --------------------------------------------------------------------------------
NOTE:  Once a redemption  is initiated  and a  confirmation  number  given,  the
transaction CANNOT be canceled.
- --------------------------------------------------------------------------------
<PAGE>

46

HOW TO REQUEST A REDEMPTION

You can  request a  redemption  from your Fund  account  in one of two ways:  by
telephone (sell, but not exchange), or by mail.

     The  Vanguard  funds  whose  shares you cannot  exchange by  telephone  are
VANGUARD  U.S.  STOCK  INDEX  FUNDS,  VANGUARD  BALANCED  INDEX  FUND,  VANGUARD
INTERNATIONAL  STOCK INDEX FUNDS,  VANGUARD REIT INDEX FUND, and VANGUARD GROWTH
AND INCOME FUND. These funds do, however, permit telephone exchanges within IRAs
and other retirement accounts.
- --------------------------------------------------------------------------------
TELEPHONE REQUESTS [TELEPHONE]
Call Vanguard  Tele-Account 24 hours a day--or your assigned  Service  Associate
during business hours--to sell shares.
- --------------------------------------------------------------------------------
SPECIAL  INFORMATION:  We will automatically  establish the telephone redemption
option for your  account,  unless you instruct us  otherwise  in writing.  While
telephone  redemption is easy and convenient,  this account  feature  involves a
risk of loss from  unauthorized or fraudulent  transactions.  Vanguard will take
reasonable  precautions  to protect your  account from fraud.  You should do the
same by keeping your account information  private and immediately  reviewing any
account  statements  that  we  send  to  you.  Make  sure  to  contact  Vanguard
immediately about any transaction you believe to be unauthorized.
- --------------------------------------------------------------------------------
We reserve the right to refuse a telephone redemption if the caller is unable to
provide:
- -    The ten-digit account number.
- -    The name and address exactly as registered on the account.
- -    The primary Social Security or employer identification number as registered
     on the account.

- -    The Personal  Identification  Number (PIN),  if applicable  (for  instance,
     Tele-Account).

     Please note that Vanguard will not be  responsible  for any account  losses
due to telephone  fraud, so long as we have taken reasonable steps to verify the
caller's identity.  If you wish to remove the telephone  redemption feature from
your account, please notify us in writing.
- --------------------------------------------------------------------------------
A NOTE ON  UNUSUAL  CIRCUMSTANCES
Vanguard  reserves the right to revise or  terminate  the  telephone  redemption
privilege at any time,  without notice.  In addition,  Vanguard can stop selling
shares or postpone  payment at times when the New York Stock  Exchange is closed
or under any emergency  circumstances  as determined by the U.S.  Securities and
Exchange Commission.  If you experience difficulty making a telephone redemption
during  periods  of  drastic  economic  or market  change,  you can send us your
request  by  regular or express  mail.  Follow  the  instructions  on selling or
exchanging shares by mail in this section.
- --------------------------------------------------------------------------------
MAIL REQUESTS [ENVELOPE]
All Account Types Except Retirement:
Send a letter of instruction signed by all registered  account holders.  Include
the fund name and  account  number and (if you are  selling) a dollar  amount or
number  of shares  OR (if you are  exchanging)  the name of the fund you want to
exchange  into and a dollar  amount or number of  shares.  To  exchange  into an
account  with a different  registration  (including a different  name,  address,
taxpayer identification number, or account type), you must provide Vanguard with
written  instructions  that  include the  guaranteed  signatures  of all current
owners of the fund from which you wish to redeem.
<PAGE>

                                                                              47


First-class mail to:               Express or Registered mail to:
The Vanguard Group                 The Vanguard Group
P.O. Box 2900                      100 Vanguard Boulevard
Valley Forge, PA 19482-2900        Malvern, PA 19355-2331

- --------------------------------------------------------------------------------
A NOTE ON LARGE REDEMPTIONS
It is important that you call Vanguard  before you redeem a large dollar amount.
It is our responsibility to consider the interests of all fund shareholders, and
so we reserve the right to delay  delivery of your  redemption  proceeds--up  to
seven days--if the amount may disrupt the Fund's operation or performance.
     If you redeem more than  $250,000  worth of Fund  shares  within any 90-day
period,  the  Fund  reserves  the  right  to pay  part or all of the  redemption
proceeds above $250,000  in-kind,  i.e., in securities,  rather than in cash. If
payment is made in-kind,  you may incur  brokerage  commissions  if you elect to
sell the securities for cash.
- --------------------------------------------------------------------------------

OPTIONS FOR REDEMPTION PROCEEDS
You may receive your redemption  proceeds in one of two ways: check, or exchange
to another Vanguard fund.
- --------------------------------------------------------------------------------
CHECK REDEMPTIONS
Normally,  Vanguard  will  mail  your  check  within  two  business  days  of  a
redemption.
- --------------------------------------------------------------------------------
EXCHANGE REDEMPTIONS
As described  above, an exchange  involves using the proceeds of your redemption
to purchase shares of another Vanguard fund.
- --------------------------------------------------------------------------------

FOR OUR MUTUAL PROTECTION
For your best interests and ours, Vanguard applies these additional requirements
to redemptions:

REQUEST IN "GOOD ORDER"
All redemption requests must be received by Vanguard in "good order." This means
that your request must include:
- -    The Fund name and account number.
- -    The amount of the transaction (in dollars or shares).
- -    Signatures  of all owners  exactly as  registered  on the account (for mail
     requests).
- -    Signature guarantees (if required).*
- -    Any supporting legal documentation that may be required.
- -    Any outstanding certificates representing shares to be redeemed.

*For instance,  a signature guarantee must be provided by all registered account
 shareholders when redemption  proceeds are to be sent to a different  person or
 address. A signature guarantee can be obtained from most commercial and savings
 banks,  credit  unions,  trust  companies, or  member  firms of  a  U.S.  stock
 exchange.

TRANSACTIONS ARE PROCESSED AT THE NEXT-DETERMINED SHARE PRICE AFTER VANGUARD HAS
RECEIVED ALL REQUIRED INFORMATION.
- --------------------------------------------------------------------------------
LIMITS ON ACCOUNT ACTIVITY
Because  excessive account  transactions can disrupt  management of the Fund and
increase the Fund's costs for all shareholders, Vanguard limits account activity
as follows:
- -    You may make no more than TWO  SUBSTANTIVE  "ROUND TRIPS"  THROUGH THE FUND
     during any 12-month period.
<PAGE>

48

- -    Your round trips through the Fund must be at least 30 days apart.
- -    The Fund may refuse a share purchase at any time, for any reason.
- -    Vanguard may revoke an investor's telephone exchange privilege at any time,
     for any reason.

     A "round trip" is a redemption  from the Fund  followed by a purchase  back
into the Fund.  Also,  a "round trip" covers  transactions  accomplished  by any
combination  of methods,  including  transactions  conducted by check,  wire, or
exchange to/from another Vanguard fund. "Substantive" means a dollar amount that
Vanguard  determines,  in  its  sole  discretion,  could  adversely  affect  the
management of the Fund.
- --------------------------------------------------------------------------------
ALL TRADES ARE FINAL
Vanguard  will not cancel any  transaction  request  (including  any purchase or
redemption)  that we believe to be authentic once the request has been initiated
and a confirmation number assigned.
- --------------------------------------------------------------------------------
UNCASHED CHECKS
Please cash your distribution or redemption  checks promptly.  Vanguard will not
pay interest on uncashed checks.
- --------------------------------------------------------------------------------


TRANSFERRING REGISTRATION

You can  transfer  the  registration  of your Fund  shares to  another  owner by
completing a transfer form and sending it to Vanguard.


First-class mail to:               Express or Registered mail to:
The Vanguard Group                 The Vanguard Group
P.O. Box 2900                      100 Vanguard Boulevard
Valley Forge, PA 19482-2900        Malvern, PA 19355-2331

- --------------------------------------------------------------------------------


FUND AND ACCOUNT UPDATES

STATEMENTS AND REPORTS
We will send you account and tax  statements to help you keep track of your Fund
account  throughout  the year as well as when you are preparing  your income tax
returns.

     In addition,  you will receive financial reports about a Fund twice a year.
These comprehensive reports include an assessment of the Fund's performance (and
a comparison to its industry benchmark), an overview of the financial markets, a
report from the adviser,  and the Fund's  financial  statements  which include a
listing of the Fund's holdings.
     To keep  each  Fund's  costs as low as  possible  (so  that  you and  other
shareholders can keep more of the Fund's investment earnings), Vanguard attempts
to  eliminate  duplicate  mailings  to the same  address.  When two or more Fund
shareholders  have the same last name and address,  we send just one Fund report
to that address--instead of mailing separate reports to each shareholder. If you
want  us  to  send  separate  reports,  notify  our  Institutional  Division  at
1-888-809-8102.

- --------------------------------------------------------------------------------
CONFIRMATION STATEMENT
Sent each time you buy,  sell, or exchange  shares;  confirms the trade date and
the amount of your transaction.
- --------------------------------------------------------------------------------
<PAGE>

                                                                              49

- --------------------------------------------------------------------------------
PORTFOLIO SUMMARY [BOOKLET]
Mailed  quarterly for most  accounts;  shows the market value of your account at
the close of the statement period, as well as distributions,  purchases,  sales,
and exchanges for the current calendar year.
- --------------------------------------------------------------------------------
FUND FINANCIAL REPORTS
Mailed in February and August for all nine Funds.
- --------------------------------------------------------------------------------
TAX STATEMENTS
Generally  mailed in January;  report previous year's dividend and capital gains
distributions,  proceeds from the sale of shares, and distributions from IRAs or
other retirement accounts.
- --------------------------------------------------------------------------------


MANDATORY CONVERSION TO INSTITUTIONAL OR INVESTOR SHARES

Vanguard  Institutional  Index Fund  reserves the right to convert an investor's
Institutional  Plus  Shares  into  Institutional  Shares  of  the  Fund  if  the
investor's  account  balance  falls  below  $200  million.   In  addition,   the
Institutional   Index  Fund   reserves   the  right  to  redeem  an   investor's
Institutional  Shares if the investor's account balance falls below $10 million.
The Total Stock Market,  Extended Market, Mid-Cap,  Small-Cap,  Value, Small-Cap
Value,  Growth,  and  Small-Cap  Growth  Index  Funds each  reserve the right to
convert an investor's Institutional Shares into Investor Shares of the same Fund
if the investor's  account balance falls below $10 million.  Any such conversion
will be preceded by written notice to the investor.  No transaction  fee will be
imposed on share-class conversions.

<PAGE>

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<PAGE>

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<PAGE>

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<PAGE>

GLOSSARY OF INVESTMENT TERMS

ACTIVE MANAGEMENT
An investment approach that seeks to exceed the average returns of the financial
markets.  Active  managers  rely on research,  market  forecasts,  and their own
judgment and experience in selecting securities to buy and sell.


CAPITAL GAINS DISTRIBUTION
Payment to mutual fund  shareholders of gains realized on securities that a fund
has sold at a profit, minus any realized losses.


CASH RESERVES
Cash deposits,  short-term  bank deposits,  and money market  instruments  which
include U.S.  Treasury bills,  bank  certificates  of deposit (CDs),  repurchase
agreements, commercial paper, and banker's acceptances.

COMMON STOCK
A security  representing  ownership  rights in a  corporation.  A stockholder is
entitled  to share in the  company's  profits,  some of which may be paid out as
dividends.

DIVIDEND INCOME
Payment to  shareholders  of income from  interest or  dividends  generated by a
fund's investments.



EXPENSE RATIO
The  percentage  of a fund's  average net assets used to pay its  expenses.  The
expense ratio  includes  management  fees,  administrative  fees,  and any 12b-1
distribution fees.


GROWTH STOCK FUND
A mutual fund that emphasizes stocks of companies believed to have above-average
prospects for growth.  Reflecting market expectations for superior growth, these
stocks typically have low dividend yields and  above-average  prices in relation
to such factors as revenue, earnings, and book value.


INDEX
An unmanaged group of securities whose overall performance is used as a standard
to measure investment performance.

INVESTMENT ADVISER
An  organization  that  makes  the  day-to-day   decisions  regarding  a  fund's
investments.



NET ASSET VALUE (NAV)
The market value of a mutual fund's total assets, minus liabilities,  divided by
the  number of shares  outstanding.  The value of a single  share is called  its
share value or share price.

PASSIVE MANAGEMENT
A low-cost  investment strategy in which a mutual fund attempts to match--rather
than  outperform--a  particular  stock  or bond  market  index.  Also  known  as
indexing.




SECURITIES
Stocks,  bonds,  money market  instruments,  and  interests in other  investment
vehicles.


TOTAL RETURN
A percentage change,  over a specified time period, in a mutual fund's net asset
value,  with the ending net asset value adjusted to account for the reinvestment
of all distributions of dividends and capital gains.


VALUE STOCK FUND
A mutual fund that  emphasizes  stocks of companies  whose growth  prospects are
generally   regarded  as  subpar  by  the  market.   Reflecting   these   market
expectations,  the  prices  of  value  stocks  typically  are  below-average  in
comparison  with such  factors as  earnings  and book  value,  and these  stocks
typically have above-average dividend yields.


VOLATILITY
The  fluctuations  in value of a mutual  fund or other  security.  The greater a
fund's volatility, the wider the fluctuations between its high and low prices.

YIELD
Income  (interest  or  dividends)  earned  by  an  investment,  expressed  as  a
percentage of the investment's price.
<PAGE>

                                                     [SHIP]
                                                     [THE VANGUARD GROUP(R)]
                                                     Institutional Division
                                                     Post Office Box 2900
                                                     Valley Forge, PA 19482-2900

FOR MORE INFORMATION
If you'd like more information about
Vanguard Institutional Index Fund or
Vanguard U.S. Stock Index Funds,
the following documents are
available free upon request:


ANNUAL/SEMIANNUAL REPORTS
TO SHAREHOLDERS
Additional information about the
Funds' investments is available in
the Funds' annual and semiannual
reports to shareholders. (The
Institutional Index Fund's reports are
separate from those of the U.S.
Stock Index Funds.)


STATEMENT OF ADDITIONAL
INFORMATION (SAI)
The SAI provides more detailed
information about the Funds. (The
SAI for the Institutional Index Fund
is separate from that of the U.S.
Stock Index Funds.)

The current annual and semiannual
reports and the SAIs are
incorporated by reference into
(and are thus legally a part of)
this prospectus.

To receive a free copy of the latest
annual or semiannual report or the
SAI, or to request additional
information about the Funds or other
Vanguard funds, please contact us
as follows:

If you are an Individual Investor:
THE VANGUARD GROUP
INVESTOR INFORMATION
DEPARTMENT
P.O. BOX 2900
VALLEY FORGE, PA 19482-2900

TELEPHONE:
1-800-662-7447 (SHIP)

TEXT TELEPHONE:
1-800-952-3335

If you are a client of Vanguard's
Institutional Division:
THE VANGUARD GROUP
INSTITUTIONAL INVESTOR
INFORMATION
P.O. BOX 2900
VALLEY FORGE, PA 19482-2900

TELEPHONE:
1-888-809-8102

WORLD WIDE WEB:
WWW.VANGUARD.COM

If you are a current Fund shareholder
and would like information about
your account, account transactions,
and/or account statements,
please call:

CLIENT SERVICES DEPARTMENT
TELEPHONE:
1-800-662-2739 (CREW)

TEXT TELEPHONE:
1-800-749-7273

INFORMATION PROVIDED BY THE
SECURITIES AND EXCHANGE
COMMISSION (SEC)

You can review and copy information
about the Funds (including the SAI)
at the SEC's Public Reference Room
in Washington, DC. To find out more
about this public service, call the
SEC at 1-202-942-8090. Reports and
other information about the Funds
are also available on the SEC's
website (www.sec.gov), or you can
receive copies of this information,
for a fee, by electronic request at
the following e-mail address:
[email protected], or by writing the
Public Reference Section, Securities
and Exchange Commission,
Washington, DC 20549-0102.


Vanguard Institutional Index Fund's
Investment Company Act
file number: 811-6093

Vanguard U.S. Stock Index Funds'
Investment Company Act
file number: 811-2652

(C) 2000 The Vanguard Group, Inc.
All rights reserved.
Vanguard Marketing Corporation,
Distributor.

I854N-04/21/2000
<PAGE>

                                     PART B

                      VANGUARD(R) INSTITUTIONAL INDEX FUND
                                   (THE FUND)

                      STATEMENT OF ADDITIONAL INFORMATION

                                 APRIL 21, 2000


This Statement is not a prospectus  but should be read in  conjunction  with the
Fund's  Prospectus dated April 21, 2000, as may be amended from time to time. To
obtain,  without  charge,  the Prospectus or an additional 1999 Annual Report to
Shareholders,   which  contains  the  Fund's  financial   statements  as  hereby
incorporated by reference, please call:



                   INSTITUTIONAL INVESTOR SERVICES DEPARTMENT
                                 1-800-523-8066

                               TABLE OF CONTENTS

DESCRIPTION OF THE FUND......................................................B-1
INVESTMENT POLICIES..........................................................B-3
FUNDAMENTAL INVESTMENT LIMITATIONS...........................................B-7
PURCHASE OF SHARES...........................................................B-8
SHARE PRICE..................................................................B-9
REDEMPTION OF SHARES........................................................B-10
MANAGEMENT OF THE FUND......................................................B-10
PORTFOLIO TRANSACTIONS......................................................B-13
FINANCIAL STATEMENTS........................................................B-13
YIELD AND TOTAL RETURN......................................................B-13
COMPARATIVE INDEXES.........................................................B-15


                            DESCRIPTION OF THE FUND

ORGANIZATION

The  Fund was  organized  as a  Pennsylvania  business  trust  in 1990,  and was
reorganized as a Delaware  business trust in July,  1998. The Fund is registered
with the United States Securities and Exchange Commission (the Commission) under
the  Investment  Company Act of 1940 (the 1940 Act) as an open-end,  diversified
management  investment  company.  It  currently  offers the  following  fund and
classes of shares:

                      Vanguard Institutional Index Fund--
               Institutional Shares and Institutional Plus Shares

     The Fund has the  ability to offer  additional  funds or classes of shares.
There is no limit on the number of full and fractional  shares that the Fund may
issue for a single fund or class of shares.

SERVICE PROVIDERS


     CUSTODIAN.   First  Union  National  Bank,   PA4943,   530  Walnut  Street,
Philadelphia,  Pennsylvania 19106, serves as the Fund's custodian. The custodian
is  responsible  for  maintaining  the Fund's  assets and keeping all  necessary
accounts and records of Fund assets.


     INDEPENDENT ACCOUNTANTS.  PricewaterhouseCoopers LLP, 30 South 17th Street,
Philadelphia,  Pennsylvania 19103, serves as the Fund's independent accountants.
The accountants audit the Fund's financial  statements and provide other related
services.

     TRANSFER  AND   DIVIDEND-PAYING   AGENT.  The  Fund's  transfer  agent  and
dividend-paying  agent is The Vanguard  Group,  Inc.,  100  Vanguard  Boulevard,
Malvern, Pennsylvania 19355.

                                      B-1
<PAGE>

CHARACTERISTICS OF THE FUND'S SHARES

     RESTRICTIONS  ON HOLDING OR DISPOSING OF SHARES.  There are no restrictions
on the right of  shareholders  to retain or dispose of the Fund's shares,  other
than the possible future  termination of the Fund. The Fund may be terminated by
reorganization  into another mutual fund or by liquidation  and  distribution of
the assets.  Unless terminated by  reorganization or liquidation,  the Fund will
continue indefinitely.

     SHAREHOLDER  LIABILITY.  The Fund is organized  under  Delaware law,  which
provides  that  shareholders  of a  business  trust  are  entitled  to the  same
limitations of personal  liability as  shareholders  of a corporation  organized
under  Delaware  law.  Effectively,  this means that a  shareholder  will not be
personally liable for payment of the Fund's debts except by reason of his or her
own conduct or acts. In addition,  a shareholder could incur a financial loss on
account of a Fund  obligation  only if the Fund itself had no  remaining  assets
with which to meet such  obligation.  We believe that the  possibility of such a
situation arising is extremely remote.


     DIVIDEND  RIGHTS.  The shareholders of the Fund are entitled to receive any
dividends or other  distributions  declared by the Fund. No shares have priority
or preference over any other shares with respect to distributions. Distributions
will be made  from the  assets  of the  Fund,  and will be paid  ratably  to all
shareholders  of the Fund (or  class)  according  to the number of shares of the
Fund (or class) held by  shareholders  on the record date.  The amount of income
dividends  per  share  may  vary  between  separate  share  classes  based  upon
differences  in the way  that  expenses  are  allocated  between  share  classes
pursuant to the Fund's multiple class plan.

     VOTING RIGHTS. The Fund's shareholders are entitled to vote on a matter if:
(i) a shareholder  vote is required under the 1940 Act; (ii) the matter concerns
an  amendment  to the  Declaration  of Trust  that would  adversely  affect to a
material degree the rights and preferences of the shares of any class or series;
or (iii) the  Trustees  determine  that it is necessary or desirable to obtain a
shareholder  vote.  The 1940 Act  requires  a  shareholder  vote  under  various
circumstances, including to elect or remove Trustees upon the written request of
shareholders  representing  10% or more of the Fund's net assets,  and to change
any  fundamental  policy of the Fund.  Shareholders of the Fund receive one vote
for each dollar of net asset value owned on the record  date,  and a  fractional
vote for each  fractional  dollar of net asset value  owned on the record  date.
However,  only the  shares of the class  affected  by a  particular  matter  are
entitled to vote on that matter.  Voting rights are  noncumulative and cannot be
modified without a majority vote.


     LIQUIDATION  RIGHTS.  In the  event of  liquidation,  shareholders  will be
entitled to receive a pro rata share of the Fund's net assets.

     PREEMPTIVE RIGHTS. There are no preemptive rights associated with shares of
the Fund.


     CONVERSION  RIGHTS.  Shareholders of the Fund may convert their shares into
another  class of  shares of the same  fund  upon the  satisfaction  of any then
applicable eligibility requirements.


     REDEMPTION  PROVISIONS.  The Fund's redemption  provisions are described in
its  current   prospectus   and  elsewhere  in  this   Statement  of  Additional
Information.

     SINKING FUND PROVISIONS. The Fund has no sinking fund provisions.

     CALLS OR  ASSESSMENT.  The Fund's shares,  when issued,  are fully paid and
non-assessable.


TAX STATUS OF THE FUND

The Fund  intends to continue  to qualify as a  "regulated  investment  company"
under  Subchapter M of the Internal  Revenue Code. This special tax status means
that the Fund will not be liable for  federal  tax on income and  capital  gains
distributed to shareholders.  In order to preserve its tax status, the Fund must
comply with certain  requirements.  If the Fund fails to meet these requirements
in any  taxable  year,  it will  be  subject  to tax on its  taxable  income  at
corporate rates, and all distributions from earnings and profits,  including any
distributions of net tax-exempt  income and net long-term capital gains, will be
taxable to  shareholders  as ordinary  income.  In  addition,  the Fund could be
required to recognize unrealized gains, pay substantial taxes and interest,  and
make  substantial  distributions  before regaining its tax status as a regulated
investment company.

                                      B-2
<PAGE>

                               INVESTMENT POLICIES

REPURCHASE AGREEMENTS

The Fund may invest in repurchase  agreements with commercial banks,  brokers or
dealers  either for defensive  purposes due to market  conditions or to generate
income from its excess cash  balances.  A  repurchase  agreement is an agreement
under which the Fund  acquires a  fixed-income  security  (generally  a security
issued by the U.S.  Government or an agency thereof, a banker's  acceptance or a
certificate  of deposit) from a commercial  bank,  broker or dealer,  subject to
resale to the  seller  at an agreed  upon  price  and date  (normally,  the next
business day). A repurchase agreement may be considered a loan collateralized by
securities. The resale price reflects an agreed upon interest rate effective for
the period the  instrument  is held by the Fund and is unrelated to the interest
rate  on the  underlying  instrument.  In  these  transactions,  the  securities
acquired by the Fund  (including  accrued  interest  earned thereon) must have a
total value in excess of the value of the  repurchase  agreement and are held by
the Fund's custodial bank until repurchased.  In addition, the Board of Trustees
will monitor the Fund's  repurchase  agreement  transactions  generally and will
establish  guidelines  and standards for review of the  creditworthiness  of any
bank, broker or dealer party to a repurchase agreement with the Fund.


     The use of repurchase  agreements  involves certain risks. For example,  if
the other party to the agreement  defaults on its  obligation to repurchase  the
underlying  security at a time when the value of the security has declined,  the
Fund may incur a loss upon  disposition  of the security.  If the other party to
the agreement  becomes  insolvent and subject to liquidation  or  reorganization
under  bankruptcy  or other  laws,  a court may  determine  that the  underlying
security is collateral for a loan by the Fund not within the control of the Fund
and  therefore  the Fund may not be able to  substantiate  its  interest  in the
underlying  security and may be deemed an unsecured  creditor of the other party
to the agreement.  While the adviser  acknowledges  these risks,  it is expected
that they will be controlled through careful monitoring procedures.


LENDING OF SECURITIES

The Fund may lend its securities on a short-term or long-term basis to qualified
institutional  investors (typically brokers,  dealers,  banks or other financial
institutions)  who  need to  borrow  securities  in order  to  complete  certain
transactions,  such as  covering  short  sales,  avoiding  failures  to  deliver
securities,  or  completing  arbitrage  operations.  By  lending  its  portfolio
securities,  the Fund can increase its net investment income through the receipt
of interest on the loan.  Any gain or loss in the market price of the securities
loaned that might occur  during the term of the loan would be for the account of
the Fund. The terms,  the structure and the aggregate  amount of such loans must
be  consistent  with the 1940  Act,  and the  Rules  or  interpretations  of the
Commission  thereunder.  These  provisions limit the amount of securities a fund
may  lend to 33 1/3% of the  Fund's  total  assets,  and  require  that  (a) the
borrower  pledge and maintain  with the Fund  collateral  consisting  of cash, a
letter of  credit  issued by a  domestic  U.S.  bank,  or  securities  issued or
guaranteed  by the United  States  Government  having at all times not less than
100%  of the  value  of the  securities  loaned,  (b) the  borrower  add to such
collateral whenever the price of the securities loaned rises (i.e., the borrower
"marks  to the  market"  on a daily  basis),  (c) the  loan be made  subject  to
termination by the Fund at any time and (d) the Fund receive reasonable interest
on the loan (which may  include  the Fund's  investing  any cash  collateral  in
interest-bearing  short-term  investments),   any  distribution  on  the  loaned
securities and any increase in their market value. Loan arrangements made by the
Fund will comply with all other applicable  regulatory  requirements,  including
the rules of the New York Stock  Exchange,  which  rules  presently  require the
borrower, after notice, to redeliver the securities within the normal settlement
time of three business days. All relevant facts and circumstances, including the
creditworthiness  of the broker,  dealer or  institution,  will be considered in
making decisions with respect to the lending of securities, subject to review by
the Board of Trustees.

     At the  present  time,  the Staff of the  Commission  does not object if an
investment  company pays  reasonable  negotiated  fees in connection with loaned
securities,  so long as such  fees  are set  forth  in a  written  contract  and
approved by the investment company's trustees.  In addition,  voting rights pass
with the loaned  securities,  but if a material  event  occurs that  affects the
securities on loan, the Fund must call the loan and vote the securities.

                                      B-3
<PAGE>

TEMPORARY INVESTMENTS

The Fund may take temporary  defensive  measures that are inconsistent  with the
Fund's normal fundamental or non-fundamental  investment policies and strategies
in response to adverse market,  economic,  political or other  conditions.  Such
measures could include investments in (a) highly liquid short-term  fixed-income
securities issued by or on behalf of municipal or corporate issuers, obligations
of the U.S. Government and its agencies, commercial paper, and bank certificates
of  deposit;  (b) shares of other  investment  companies  which have  investment
objectives  consistent  with  those  of  the  Fund;  (c)  repurchase  agreements
involving any such securities; and (d) other money market instruments.  There is
no limit on the extent to which the Fund may take temporary  defensive measures.
In taking such measures, the Fund may fail to achieve its investment objective.

VANGUARD INTERFUND LENDING PROGRAM

The  Commission  has issued an  exemptive  order  permitting  the Fund and other
Vanguard funds to  participate in Vanguard's  interfund  lending  program.  This
program  allows the  Vanguard  funds to borrow money from and loan money to each
other for temporary or emergency purposes. The program is subject to a number of
conditions,  including  the  requirement  that no fund may  borrow or lend money
through the program  unless it receives a more  favorable  interest rate than is
available  from a typical bank for a  comparable  transaction.  In  addition,  a
Vanguard fund may participate in the program only if and to the extent that such
participation  is  consistent  with the fund's  investment  objective  and other
investment  policies.   The  Boards  of  Trustees  of  the  Vanguard  funds  are
responsible  for  ensuring  that  the  interfund  lending  program  operates  in
compliance with all conditions of the Commission's exemptive order.


ILLIQUID SECURITIES

The Fund may invest up to 15% of its net assets in illiquid securities. Illiquid
securities are securities that the Fund may not be able to sell or dispose of in
the ordinary course of business within seven business days at approximately  the
value at which they are being carried on the Fund's books.

FUTURES CONTRACTS

The Fund may enter  into  futures  contracts,  options,  and  options on futures
contracts  for  the  purpose  of  simulating   full   investment   and  reducing
transactions  costs.  The Fund does not use futures or options  for  speculative
purposes. The Fund will only use futures and options to simulate full investment
in the  underlying  index  while  retaining a cash  balance for fund  management
purposes.  Futures  contracts  provide  for the  future  sale by one  party  and
purchase  by another  party of a  specified  amount of a specific  security at a
specified  future  time and at a specified  price.  Futures  contracts  that are
standardized as to maturity date and underlying  financial instrument are traded
on national futures exchanges. Futures exchanges and trading are regulated under
the Commodity Exchange Act by the Commodity Futures Trading Commission (CFTC), a
U.S. Government Agency. Assets committed to futures contracts will be segregated
to the extent required by law.

     Although  futures  contracts  by their  terms call for actual  delivery  or
acceptance of the underlying securities,  in most cases the contracts are closed
out before the settlement date without the making or taking of delivery. Closing
out an open futures position is done by taking an opposite position  ("buying" a
contract  that has  previously  been "sold," or "selling" a contract  previously
purchased)  in an  identical  contract  to  terminate  the  position.  Brokerage
commissions are incurred when a futures contract is bought or sold.

     Futures traders are required to make a good faith margin deposit in cash or
government  securities  with a broker or custodian to initiate and maintain open
positions  in  futures  contracts.  A  margin  deposit  is  intended  to  assure
completion of the contract  (delivery or acceptance of the underlying  security)
if it is not terminated  prior to the specified  delivery date.  Minimal initial
margin  requirements are established by the futures exchange and may be changed.
Brokers may  establish  deposit  requirements  that are higher than the exchange
minimums. Futures contracts are customarily purchased and sold on deposits which
may range upward from less than 5% of the value of the contract being traded.

     After a futures contract  position is opened,  the value of the contract is
marked to market daily. If the futures contract price changes to the extent that
the  margin  on  deposit  does  not  satisfy  margin  requirements,  payment  of
additional  "variation"  margin  will be  required.  Conversely,  change  in the
contract  value may reduce the  required  margin,  resulting  in a repayment  of
excess margin to the

                                      B-4
<PAGE>

contract  holder.  Variation  margin  payments  are made to and from the futures
broker  for as long as the  contract  remains  open.  The Fund  expects  to earn
interest income on its margin deposits.

     Traders in futures contracts may be broadly  classified as either "hedgers"
or   "speculators."   Hedgers  use  the  futures  markets  primarily  to  offset
unfavorable  changes  in the  value of  securities  either  held for  investment
purposes or expected to be acquired by them.  Speculators  are less  inclined to
own, or intend to purchase,  the  securities  underlying  the futures  contracts
which they trade,  and use futures  contracts with the  expectation of realizing
profits  from  fluctuations  in the prices of  underlying  securities.  The Fund
intends to use futures contracts only for bona fide hedging purposes.

     Regulations  of the CFTC  applicable  to the Fund  require  that all of its
futures  transactions  constitute bona fide hedging  transactions  except to the
extent that the aggregate initial margins and premiums required to establish any
non-hedging  positions  do not  exceed  five  percent of the value of the Fund's
portfolio. The Fund will only sell futures contracts to protect the Fund against
declines in the prices of the  securities  underlying  the futures  contracts or
purchase  contracts to protect against an increase in the price of securities it
intends to purchase. As evidence of this hedging interest, the Fund expects that
the majority of its futures  contract  purchases will be  "completed";  that is,
equivalent  amounts of related  securities will have been purchased or are being
purchased by the Fund upon sale of open futures contracts.

     Although  techniques other than the sale and purchase of futures  contracts
could be used to control the Fund's exposure to market fluctuations,  the use of
futures contracts may be a more effective means of hedging this exposure.  While
the Fund will incur commission  expenses in both opening and closing out futures
positions, these costs are lower than transaction costs incurred in the purchase
and sale of the underlying securities.

     RESTRICTIONS ON THE USE OF FUTURES CONTRACTS.  The Fund will not enter into
futures contract transactions to the extent that,  immediately  thereafter,  the
sum of its initial margin  deposits on open  contracts  exceeds 5% of the market
value of its total  assets.  In  addition,  the Fund will not enter into futures
contracts to the extent that its outstanding  obligations to purchase securities
under these contracts would exceed 20% of the Fund's total assets.

     RISK FACTORS IN FUTURES TRANSACTIONS. Positions in futures contracts may be
closed  out only on an  Exchange  that  provides  a  secondary  market  for such
futures.  However, there can be no assurance that a liquid secondary market will
exist for any particular futures contract at any specific time. Thus, it may not
be  possible  to  close a  futures  position.  In the  event  of  adverse  price
movements, the Fund would continue to be required to make daily cash payments to
maintain its required margin.  In such situations,  if the Fund has insufficient
cash, it may have to sell portfolio securities to meet daily margin requirements
at a time when it may be disadvantageous to do so. In addition,  the Fund may be
required to make delivery of the  instruments  underlying  futures  contracts it
holds.  The inability to close options and futures  positions could also have an
adverse impact on the ability to effectively  hedge.  The Fund will minimize the
risk that it will be unable to close  out a futures  contract  by only  entering
into futures that are traded on national  futures  exchanges and for which there
appears to be a liquid secondary market.

     The risk of loss in trading  futures  contracts in some  strategies  can be
substantial, due both to the low margin deposits required and the extremely high
degree of leverage involved in futures pricing.  As a result, a relatively small
price  movement in a futures  contract may result in immediate  and  substantial
loss (as well as gain) to the investor. For example, if at the time of purchase,
10% of the value of the futures  contract is deposited  as margin,  a subsequent
10% decrease in the value of the futures  contract  would result in a total loss
of the margin deposit,  before any deduction for the  transaction  costs, if the
account  were then closed out. A 15%  decrease  would  result in a loss equal to
150% of the original  margin  deposit if the contract  were closed out.  Thus, a
purchase  or sale of a futures  contract  may  result in losses in excess of the
amount  invested in the contract.  The Fund also bears the risk that the adviser
will  incorrectly  predict  future stock  market  trends.  However,  because the
futures strategy of the Fund is engaged in only for hedging purposes, the Fund's
officers do not believe that the Fund is subject to the risks of loss frequently
associated with futures  transactions.  The Fund would presumably have sustained
comparable  losses if, instead of the futures  contract,  it had invested in the
underlying financial instrument and sold it after the decline.

     Utilization  of futures  transactions  by the Fund does involve the risk of
imperfect or no correlation  where the securities  underlying  futures contracts
have different maturities than the portfolio securities being hedged. It is also
possible  that the Fund  could both lose  money on  futures  contracts  and also
experience  a decline in value of its  portfolio  securities.  There is also the
risk of

                                      B-5
<PAGE>

loss by the Fund of margin  deposits in the event of bankruptcy of a broker with
whom the Fund has an open position in a futures contract or related option.

     Most futures exchanges limit the amount of fluctuation permitted in futures
contract  prices during a single  trading day. The daily limit  establishes  the
maximum  amount that the price of a futures  contract may vary either up or down
from the previous day's settlement  price at the end of a trading session.  Once
the daily limit has been reached in a particular type of contract, no trades may
be made on that day at a price beyond that limit.  The daily limit  governs only
price  movement  during a particular  trading day and  therefore  does not limit
potential  losses,  because the limit may prevent the liquidation of unfavorable
positions.  Futures contract prices have  occasionally  moved to the daily limit
for  several  consecutive  trading  days  with  little  or no  trading,  thereby
preventing  prompt  liquidation of future  positions and subjecting some futures
traders to substantial losses.


     FEDERAL  TAX  TREATMENT  OF FUTURES  CONTRACTS.  The Fund is  required  for
Federal income tax purposes to recognize as income for each taxable year its net
unrealized  gains and losses on certain  futures  contracts as of the end of the
year as well as those  actually  realized  during the year. In these cases,  any
gain or loss recognized  with respect to a futures  contract is considered to be
60%  long-term  capital  gain or loss and 40%  short-term  capital gain or loss,
without  regard to the  holding  period  of the  contract.  Gains and  losses on
certain other futures contracts  (primarily non-U.S.  futures contracts) are not
recognized  until the  contracts  are closed and are  treated  as  long-term  or
short-term  depending on the holding  period of the  contract.  Sales of futures
contracts  which  are  intended  to  hedge  against  a  change  in the  value of
securities  held by the Fund may affect the  holding  period of such  securities
and,  consequently,  the  nature  of the  gain or loss on such  securities  upon
disposition.  The Fund may be  required  to defer the  recognition  of losses on
futures  contracts to the extent of any unrecognized  gains on related positions
held by the Fund.

     In order  for the Fund to  continue  to  qualify  for  federal  income  tax
treatment as a regulated  investment  company,  at least 90% of its gross income
for a taxable  year must be derived from  qualifying  income;  i.e.,  dividends,
interest,  income  derived  from  loans of  securities,  gains  from the sale of
securities or of foreign currencies, or other income derived with respect to the
Fund's business of investing in securities or currencies. It is anticipated that
any net gain on  futures  contracts  will be  considered  qualifying  income for
purposes of the 90% requirement.

     The Fund will  distribute  to  shareholders  annually any net capital gains
which have been recognized for federal income tax purposes (including unrealized
gains at the end of the  Fund's  fiscal  year)  on  futures  transactions.  Such
distributions  will be combined with  distributions of capital gains realized on
the Fund's other  investments and shareholders  will be advised on the nature of
the transactions.


FOREIGN INVESTMENTS

The Fund may invest in foreign  securities to the extent  necessary to carry out
its investment  strategy of holding all of the stocks that comprise the index it
tracks.  Investors should recognize that investing in foreign companies involves
certain special considerations which are not typically associated with investing
in U.S. companies.

     CURRENCY  RISK.  Since  the  stocks of  foreign  companies  are  frequently
denominated  in  foreign  currencies,  and since the Fund may  temporarily  hold
uninvested  reserves in bank  deposits in foreign  currencies,  the Fund will be
affected  favorably  by  changes  in  currency  rates  and in  exchange  control
regulations,  and may incur costs in connection with conversions between various
currencies.  The investment policies of the Fund permit it to enter into forward
foreign  currency  exchange  contracts in order to hedge the Fund's holdings and
commitments  against  changes  in the  level  of  future  currency  rates.  Such
contracts  involve an  obligation  to purchase or sell a specific  currency at a
future date at a price set at the time of the contract.


     FEDERAL TAX  TREATMENT OF NON-U.S.  TRANSACTIONS.  Special rules govern the
Federal income tax treatment of certain  transactions  denominated in terms of a
currency  other than the U.S.  dollar or determined by reference to the value of
one or more  currencies  other than the U.S.  dollar.  The types of transactions
covered by the special rules include the following:  (i) the  acquisition of, or
becoming the obligor under, a bond or other debt instrument  (including,  to the
extent provided in Treasury regulations,  preferred stock); (ii) the accruing of
certain  trade  receivables  and  payables;  and  (iii)  the  entering  into  or
acquisition  of any  forward  contract,  futures  contract,  option  or  similar
financial instrument if such instrument is not market to market. The disposition
of a currency other than the U.S. dollar by a taxpayer whose functional currency
is the U.S.  dollar is also  treated as a  transaction  subject  to the  special
currency rules. However, foreign currency-related regulated


                                      B-6
<PAGE>


futures contracts and nonequity options are generally not subject to the special
currency  rules if they are or would be treated  as sold for their  fair  market
value at year-end under the marking-to-market  rules applicable to other futures
contracts  unless an election is made to have such  currency  rules apply.  With
respect to transactions  covered by the special rules,  foreign currency gain or
loss  is  calculated  separately  from  any  gain  or  loss  on  the  underlying
transaction  and is normally  taxable as ordinary income or loss. A taxpayer may
elect to treat as capital  gain or loss  foreign  currency  gain or loss arising
from certain identified  forward  contracts,  futures contracts and options that
are  capital  assets  in the hands of the  taxpayer  and which are not part of a
straddle.  The  Treasury  Department  issued  regulations  under  which  certain
transactions  subject to the special  currency rules that are part of a "section
988 hedging  transaction"  (as defined in the Internal  Revenue Code of 1986, as
amended,  and the  Treasury  regulations)  will be  integrated  and treated as a
single  transaction or otherwise treated  consistently for purposes of the Code.
Any gain or loss attributable to the foreign currency component of a transaction
engaged in by the Fund which is not subject to the special  currency rules (such
as foreign  equity  investments  other than  certain  preferred  stocks) will be
treated as capital gain or loss and will not be segregated from the gain or loss
on the  underlying  transaction.  It is  anticipated  that some of the  non-U.S.
dollar-denominated  investments and foreign currency contracts the Fund may make
or enter into will be subject to the special currency rules described above.


     COUNTRY  RISK. As foreign  companies  are not generally  subject to uniform
accounting,  auditing and financial reporting standards and practices comparable
to those applicable to domestic companies,  there may be less publicly available
information  about certain  foreign  companies  than about  domestic  companies.
Securities of some foreign companies are generally less liquid and more volatile
than  securities  of  comparable  domestic  companies.  There is generally  less
government  supervision  and regulation of stock  exchanges,  brokers and listed
companies  than in the  U.S.  In  addition,  with  respect  to  certain  foreign
countries,  there is the possibility of expropriation or confiscatory  taxation,
political or social instability,  or diplomatic  developments which could affect
U.S. investments in those countries.

     Although the Fund will endeavor to achieve most favorable  execution  costs
in its portfolio transactions, fixed commissions on many foreign stock exchanges
are generally higher than negotiated commissions on U.S. exchanges. In addition,
it is  expected  that the  expenses  for  custodian  arrangements  of the Fund's
foreign  securities will be somewhat greater than the expenses for the custodian
arrangements for handling U.S. securities of equal value.

     Certain foreign  governments  levy  withholding  taxes against dividend and
interest  income.  Although  in some  countries  a  portion  of  these  taxes is
recoverable,  the non-recovered portion of foreign withholding taxes will reduce
the income  received from foreign  companies  held by the Fund.  However,  these
foreign  withholding taxes are not expected to have a significant  impact on the
Fund, since the Fund seeks long-term capital  appreciation and any income should
be considered incidental.


                       FUNDAMENTAL INVESTMENT LIMITATIONS

The Fund is subject to the following fundamental investment  limitations,  which
cannot be changed in any  material  way without the approval of the holders of a
majority of the Fund's shares. For these purposes,  a "majority" of shares means
the lesser of: (i) 67% or more of the votes cast, so long as shares representing
more than 50% of the Fund's net asset value are present or represented by proxy;
or (ii) shares representing more than 50% of the Fund's net asset value.

     BORROWING. The Fund may not borrow money, except for temporary or emergency
purposes in an amount not exceeding  15% of the Fund's net assets.  The Fund may
borrow  money  through  banks,  reverse  repurchase  agreements,  or  Vanguard's
interfund  lending program only, and must comply with all applicable  regulatory
conditions.  The Fund may not make any additional investments if its outstanding
borrowings exceed 5% of net assets.

     COMMODITIES.  The Fund may not invest in  commodities,  except  that it may
invest in stock  index  futures  contracts,  stock  options and options on stock
index futures contracts.  No more than 5% of the Fund's total assets may be used
as initial  margin  deposit for futures  contracts,  and no more than 20% of the
Fund's total assets may be invested in futures contracts or options at any time.

                                      B-7
<PAGE>

     DIVERSIFICATION. With respect to 75% of its total assets, the Fund may not:
(i)  purchase  more than 10% of the  outstanding  voting  securities  of any one
issuer; or (ii) purchase  securities of any issuer if, as a result, more than 5%
of the Fund's total assets would be invested in that issuer's  securities.  This
limitation  does not apply to obligations of the United States  Government,  its
agencies, or instrumentalities.

     ILLIQUID SECURITIES. The Fund may not acquire any security if, as a result,
more  than  15% of its net  assets  would be  invested  in  securities  that are
illiquid.  From time to time,  the Fund's Board of Trustees may  determine  that
certain  restricted  securities known as Rule 144A securities are liquid and not
subject to the 15% limitation.

     INDUSTRY CONCENTRATION.  The Fund may not invest more than 25% of its total
assets in any one industry.

     INVESTING FOR CONTROL. The Fund may not invest in a company for purposes of
controlling its management.

     INVESTMENT  COMPANIES.  The Fund may not  invest  in any  other  investment
company, except through a merger,  consolidation or acquisition of assets, or to
the extent permitted by Section 12 of the 1940 Act.  Investment  companies whose
shares a Fund acquires  pursuant to Section 12 must have  investment  objectives
and investment policies consistent with those of the Fund.

     LOANS. The Fund may not lend money to any person except by purchasing fixed
income  securities  that  are  publicly   distributed,   lending  its  portfolio
securities, or through Vanguard's interfund lending program.

     MARGIN.  The Fund may not purchase  securities on margin or sell securities
short,  except as  permitted  by the  Fund's  investment  policies  relating  to
commodities.

     OIL,  GAS,  MINERALS.  The Fund may not invest in  interests in oil, gas or
other mineral exploration or development programs.

     PLEDGING ASSETS. The Fund may not pledge, mortgage or hypothecate more than
15% of its net assets.


     PUTS/CALLS. The Fund may not purchase or sell put, call, straddle or spread
options, except as provided above under "Commodities."


     REAL ESTATE.  The Fund may not invest directly in real estate,  although it
may invest in securities of companies that deal in real estate.

     SENIOR  SECURITIES.  The Fund may not issue  senior  securities,  except in
compliance with the 1940 Act.

     UNDERWRITING.  The Fund may not  engage  in the  business  of  underwriting
securities  issued  by  other  persons.  The  Fund  will  not be  considered  an
underwriter when disposing of its investment securities.

     The  above-mentioned  investment  limitations  are  considered  at the time
investment securities are purchased.


                               PURCHASE OF SHARES

The Fund reserves the right in its sole  discretion (i) to suspend the offerings
of its shares,  (ii) to reject  purchase or exchange orders when in the judgment
of  management  such  rejection  is in the best  interest of the Fund,  (iii) to
impose a transaction fee on a purchase of the Fund's shares if the purchase,  in
the opinion of Vanguard, would disrupt the efficient management of the Fund, and
(iv) to reduce or waive the minimum  investment for or any other restrictions on
initial  and  subsequent  investments  for certain  fiduciary  accounts or under
circumstances  where  certain  economies  can be achieved in sales of the Fund's
shares.

     EXCHANGE OF SECURITIES  FOR SHARES OF THE FUND.  In certain  circumstances,
shares of the Fund may be purchased "in-kind," i.e., in exchange for securities,
rather than for cash.  The  securities  tendered as part of an in-kind  purchase
must be included in the Index  tracked by the Fund and each position must have a
market value of $10,000 or more.  Securities accepted by the Fund will be valued
as set forth in the Fund's  prospectus as of the time of the next  determination
of net asset value after such  acceptance.  Shares of the Fund are issued at net
asset value  determined as of the same time.  All  dividends,  subscription,  or
other rights which are reflected in the market price of

                                      B-8
<PAGE>

accepted securities at the time of valuation become the property of the Fund and
must be delivered to the Fund by the  investor  upon receipt from the issuer.  A
gain or loss for Federal  income tax purposes  would be realized by the investor
upon the exchange depending upon the cost of the securities tendered.

     The Fund will not accept securities in exchange for its shares unless:  (1)
such  securities  are, at the time of the  exchange,  eligible to be held by the
Fund;  (2) the  transaction  will not  cause  the  Fund's  weightings  to become
imbalanced  with respect to the weightings of the stocks  included in the Index;
(3) the investor  represents and agrees that all securities  offered to the Fund
are not  subject  to any  restrictions  upon  their  sale by the Fund  under the
Securities  Act of 1933,  or  otherwise;  (4) such  securities  are traded in an
unrelated  transaction  with a quoted  sales price on the same day the  exchange
valuation  is made;  (5) the quoted  sales price used as a basis of valuation is
representative (e.g., one that does not involve a trade of substantial size that
artificially  influences  the price of the  security);  and (6) the value of any
such  security  being  exchanged  will not  exceed 5% of the  Fund's  net assets
immediately prior to the transaction.

     Investors  interested  in purchasing  Fund shares  in-kind  should  contact
Vanguard.


                                  SHARE PRICE

The Fund's  share  price,  or "net asset  value" per  share,  is  calculated  by
dividing the net assets of the Fund attributed to each share class, by the total
number  of shares  outstanding  for each  share  class.  The net asset  value is
determined as of the close of the New York Stock Exchange  (generally  4:00 p.m.
Eastern time) on each day the Exchange is open for trading.

     Portfolio  securities  for which market  quotations  are readily  available
(includes those securities listed on national securities  exchanges,  as well as
those quoted on the NASDAQ Stock Market) will be valued at the last quoted sales
price on the day the valuation is made. Such securities  which are not traded on
the  valuation  date are  valued  at the mean of the bid and ask  prices.  Price
information on  exchange-listed  securities is taken from the exchange where the
security is primarily  traded.  Any foreign  securities are valued at the latest
quoted sales price available before the time when assets are valued.  Securities
may be valued on the basis of prices  provided  by a pricing  service  when such
prices are believed to reflect the fair market value of such securities.

     Short-term instruments (those acquired with remaining maturities of 60 days
or less) may be valued at cost, plus or minus any amortized discount or premium,
which approximates market value.

     Bonds  and  other  fixed-income  securities  may be  valued on the basis of
prices  provided by a pricing  service  when such prices are believed to reflect
the fair  market  value of such  securities.  The prices  provided  by a pricing
service  may be  determined  without  regard to bid or last sale  prices of each
security,  but take into  account  institutional-size  transactions  in  similar
groups of securities as well as any developments related to specific securities.

     Foreign  securities are valued at the last quoted sales price,  or the most
recently   determined  closing  price  calculated   according  to  local  market
convention, available at the time a Fund is valued. Prices are obtained from the
broadest and most representative market on which the securities trade. If events
which materially affect the value of a Fund's  investments occur after the close
of the securities  markets on which such securities are primarily traded,  those
investments may be valued by such methods as the Board of Trustees deems in good
faith to reflect fair value.

     In  determining  a Fund's  net  asset  value  per  share,  all  assets  and
liabilities  initially  expressed in foreign  currencies  will be converted into
U.S.  dollars using the  officially  quoted daily  exchange rates used by Morgan
Stanley Capital  International in calculating various benchmarking indexes. This
officially quoted exchange rate may be determined prior to or after the close of
a particular  securities  market. If such quotations are not available or do not
reflect market  conditions at the time the Fund is valued,  the rate of exchange
will be determined in accordance with policies  established in good faith by the
Board of Trustees.

     Other assets and securities  for which no quotations are readily  available
or which are restricted as to sale (or resale) are valued by such methods as the
Board of Trustees deems in good faith to reflect fair value.

     The share price for the Fund can be found daily in the mutual fund listings
of most major newspapers under the heading of "Vanguard Index Funds."

                                      B-9
<PAGE>

                              REDEMPTION OF SHARES

The Fund may suspend  redemption  privileges or postpone the date of payment (i)
during any period that the New York Stock Exchange is closed,  or trading on the
Exchange is restricted as determined by the  Commission,  (ii) during any period
when an emergency exists as defined by the Commission as a result of which it is
not reasonably practicable for the Fund to dispose of securities owned by it, or
fairly to determine the value of its assets, and (iii) for such other periods as
the Commission may permit.

     The Fund  has  made an  election  with  the  Commission  to pay in cash all
redemptions  requested by any shareholder of record limited in amount during any
90-day  period to the lesser of  $250,000 or 1% of the net assets of the Fund at
the beginning of such period.

     No charge is made by the Fund for redemptions. Shares redeemed may be worth
more or less than what was paid for them,  depending  on the market value of the
securities held by the Fund.


                             MANAGEMENT OF THE FUND

OFFICERS AND TRUSTEES

The officers of the Fund manage its day-to-day operations and are responsible to
the Fund's Board of Trustees.  The Trustees set broad  policies for the Fund and
choose its officers. The following is a list of the Trustees and officers of the
Fund and a statement of their present positions and principal occupations during
the past five years. As a group,  the Fund's Trustees and officers own less than
1% of the outstanding shares of the Fund. Each Trustee also serves as a Director
of The  Vanguard  Group,  Inc.,  and as a  Trustee  of  each  of the  103  funds
administered  by Vanguard (102 in the case of Mr.  Malkiel and 93 in the case of
Mr.  MacLaury).  The mailing address of the Trustees and officers of the Fund is
Post Office Box 876, Valley Forge, PA 19482.


JOHN J. BRENNAN, (DOB: 7/29/1954) Chairman Chief Executive Officer & Trustee*
Chairman,  Chief Executive Officer and Director of The Vanguard Group, Inc., and
Trustee of each of the investment companies in The Vanguard Group.

JOANN  HEFFERNAN  HEISEN,  (DOB:   1/25/1950)  Trustee
Vice President, Chief Information Officer, and member of the Executive Committee
of Johnson & Johnson (Pharmaceuticals/Consumer  Products), Director of Johnson &
Johnson*MERCK Consumer Pharmaceuticals Co., The Medical Center at Princeton, and
Women's Research and Education Institute.

BRUCE K. MACLAURY, (DOB: 5/7/1931) Trustee
President  Emeritus  of  The  Brookings  Institution  (Independent  Non-Partisan
Research  Organization);  Director of American  Express Bank, Ltd., The St. Paul
Companies, Inc. (Insurance and Financial Services), and National Steel Corp.

BURTON G. MALKIEL, (DOB: 8/28/1932) Trustee
Chemical Bank Chairman's Professor of Economics, Princeton University;  Director
of Prudential Insurance Co. of America, Banco Bilbao Gestinova, Baker Fentress &
Co.  (Investment  Management),  The Jeffrey Co.  (Holding  Company),  and Select
Sector SPDR Trust (Exchange-Traded Mutual Fund).

ALFRED M. RANKIN, JR., (DOB: 10/8/1941) Trustee
Chairman,  President,  Chief Executive Officer, and Director of NACCO Industries
(Machinery/Coal/Appliances),  and  Director  of  The  BFGoodrich  Co.  (Aircraft
Systems/Manufacturing/Chemicals).

JOHN C. SAWHILL, (DOB: 6/12/1936) Trustee
President  and Chief  Executive  Officer of The Nature  Conservancy  (Non-Profit
Conservation Group);  Director of Pacific Gas and Electric Co., Procter & Gamble
Co., NACCO Industries (Machinery/Coal/Appliances),  and Newfield Exploration Co.
(Energy); formerly, Director and Senior Partner of McKinsey & Co., and President
of New York University.

JAMES O. WELCH, JR., (DOB: 5/13/1931) Trustee
Retired Chairman of Nabisco Brands, Inc. (Food Products);  retired Vice Chairman
and  Director  of RJR  Nabisco  (Food and  Tobacco  Products);  Director of TECO
Energy, Inc., and Kmart Corp.

                                      B-10
<PAGE>


J. LAWRENCE WILSON, (DOB: 3/2/1936) Trustee
Retired Chairman of Rohm & Haas Co. (Chemicals);  Director of Cummins Engine Co.
(Diesel Engine Company), The Mead Corp. (Paper Products), and AmeriSource Health
Corp.; and Trustee of Vanderbilt University.


RAYMOND J. KLAPINSKY, (DOB: 12/7/1938) Secretary*
Managing Director of The Vanguard Group, Inc.;  Secretary of The Vanguard Group,
Inc. and of each of the investment companies in The Vanguard Group.

THOMAS J. HIGGINS, (DOB: 5/21/1957) Treasurer*
Principal  of The Vanguard  Group,  Inc.;  Treasurer  of each of the  investment
companies in The Vanguard Group.

ROBERT D. SNOWDEN, (DOB: 9/4/1961) Controller*
Principal of The Vanguard  Group,  Inc.;  Controller  of each of the  investment
companies in The Vanguard Group.
- ---------
*Officers of the Fund are "interested persons" as defined in the 1940 Act.

TRUSTEE COMPENSATION

The  same  individuals  serve as  Trustees  of all  Vanguard  Trusts  (with  two
exceptions,  which  are  noted  in the  table  below),  and  each  Trust  pays a
proportionate share of Trustees' compensation.  The Trusts employ their officers
on a shared basis,  as well.  However,  officers are compensated by The Vanguard
Group, Inc., not the Trusts.

     INDEPENDENT    TRUSTEES.    The   Trusts   compensate   their   independent
Trustees--that  is, the ones who are not also  officers of the  Trust--in  three
ways:

- -    The  independent  Trustees  receive an annual fee for their  service to the
     Trusts,  which is subject to  reduction  based on absences  from  scheduled
     Board meetings.
- -    The  independent  Trustees are reimbursed for the travel and other expenses
     that they incur in attending Board meetings.
- -    Upon retirement,  the independent  Trustees receive an aggregate annual fee
     of  $1,000  for each year  served  on the  Board,  up to  fifteen  years of
     service.  This annual fee is paid for ten years  following  retirement,  or
     until each Trustee's death.

     "INTERESTED"  TRUSTEE.  Mr. Brennan serves as a Trustee, but is not paid in
this capacity. He is however, paid in his role as officer of The Vanguard Group,
Inc.

     COMPENSATION TABLE. The following table provides  compensation  details for
each of the Trustees.  We list the amounts paid as  compensation  and accrued as
retirement benefits by the Fund for each Trustee.  In addition,  the table shows
the total  amount of benefits  that we expect each  Trustee to receive  from all
Vanguard Trusts upon  retirement,  and the total amount of compensation  paid to
each Trustee by all Vanguard  Trusts.  All  information  shown is for the fiscal
year ended December 31, 1999.

                                      B-11
<PAGE>


                               COMPENSATION TABLE
                            INSTITUTIONAL INDEX FUND

                                   ESTIMATED ANNUAL      TOTAL COMPENSATION FROM
                                    BENEFITS UPON        ALL VANGUARD FUNDS PAID
    NAMES OF TRUSTEES                RETIREMENT              TO TRUSTEES(1)
- --------------------------------------------------------------------------------
John C. Bogle(2). . . . . . .            None                      None
John J. Brennan . . . . . . .            None                      None
JoAnn Heffernan Heisen. . . .         $15,000                   $80,000
Bruce K. MacLaury . . . . . .         $12,000                   $75,000
Burton G. Malkiel . . . . . .         $15,000                   $80,000
Alfred M. Rankin, Jr. . . . .         $15,000                   $80,000
John C. Sawhill . . . . . . .         $15,000                   $80,000
James O. Welch, Jr. . . . . .         $15,000                   $80,000
J. Lawrence Wilson. . . . . .         $15,000                   $80,000
- ---------
(1)  The amounts reported in this column reflect the total  compensation paid to
     each Trustee for his or her service as Trustee of 103  Vanguard  funds (102
     in the case of Mr. Malkiel; 93 in the case of Mr. MacLaury).

(2)  Mr. Bogle has retired from the Fund's Board, effective December 31, 1999.

THE VANGUARD GROUP

The Fund  currently  employs The  Vanguard  Group,  Inc.  (Vanguard)  to provide
management,  administrative,  and investment  advisory  services.  Vanguard also
provides  virtually  all  of  the  corporate  management,   administrative,  and
distribution services for The Vanguard Group of Investment  Companies,  a family
of more than 100 funds.  Vanguard also provides  investment advisory services on
an at-cost basis to several of the Vanguard funds.

     Vanguard  employs  a  supporting  staff of  management  and  administrative
personnel  needed  to  provide  the  requisite  services  to the  Fund  and also
furnishes the Fund with the necessary office space, furnishings and equipment.

     Vanguard has adopted a Code of Ethics designed to prevent employees who may
have access to nonpublic  information  about the trading  activities of the Fund
(access persons) from profiting from that  information.  The Code permits access
persons to invest in  securities  for their own accounts,  including  securities
that may be held by the Fund, but places substantive and procedural restrictions
on their trading activities.  For example, the Code requires that access persons
of the Fund receive advance  approval for every  securities trade to ensure that
there is no conflict with the trading activities of the Fund.

     The Fund receives all investment advisory services from Vanguard.  Vanguard
manages the investment and  reinvestment  of the Fund's assets and  continuously
reviews,  supervises, and administers the Fund's investment program with respect
to those assets. Vanguard discharges its responsibilities subject to the control
of the officers and Trustees of the Fund.

     Vanguard also provides investment advisory services to several other funds.
Total assets under management by Vanguard were  approximately  $371.4 billion as
of  December  31,  1999.  The  Fund  is not  actively  managed,  but is  instead
administered by Vanguard using computerized, quantitative techniques.

     Under the terms of a Service and Advisory  Agreement,  Vanguard pays all of
the Fund's expenses, except for taxes and brokerage commissions.  For the fiscal
years ended  December  31, 1997,  1998,  and 1999,  the Fund paid  approximately
$8,915,000,  $12,055,000, and $16,858,000 respectively, to Vanguard for services
rendered under the Service and Advisory Agreement.


                                      B-12
<PAGE>

                             PORTFOLIO TRANSACTIONS

In placing portfolio transactions,  The Vanguard Group uses its best judgment to
choose the broker most capable of providing the brokerage  services necessary to
the obtain best available price and most favorable execution. The full range and
quality  of  brokerage   services  available  are  considered  in  making  these
determinations.  In those instances where it is reasonably  determined that more
than one  broker  can offer the  brokerage  services  needed to obtain  the best
available price and most favorable  execution,  consideration  is given to those
brokers  which supply  statistical  information  and provide  other  services in
addition to execution services to the Fund.

     Since the Fund does not market its shares through  intermediary  brokers or
dealers,  it is not the Fund's  practice  to  allocate  brokerage  or  principal
business  on the basis of sales of its  shares  which may be made  through  such
firms.   However,   the  Fund  may  place   portfolio   orders  with   qualified
broker-dealers  who  recommend  the Fund to clients,  and may,  when a number of
brokers  and  dealers  can  provide  best price and  execution  on a  particular
transaction, consider the sale of Fund shares by a broker or dealer in selecting
among broker dealers.

     For the fiscal years ended December 31, 1997, 1998, and 1999, the Fund paid
$820,969, $1,356,000, and $1,455,950 respectively, in brokerage commissions.


                              FINANCIAL STATEMENTS

The Fund's financial  statements as of and for the year ended December 31, 1999,
appearing  in the  Vanguard  Institutional  Index  Fund  1999  Annual  Report to
Shareholders,  and the report thereon of PricewaterhouseCoopers LLP, independent
accountants,  also  appearing  therein,  are  incorporated  by reference in this
Statement of  Additional  Information.  For a more  complete  discussion  of the
performance,  please see the Fund's Annual Report to Shareholders,  which may be
obtained without charge.


                             YIELD AND TOTAL RETURN

The  annualized  yield for the  Institutional  Shares of the Fund for the thirty
days  ended  December  31,  1999  was  1.10%.   The  annualized  yield  for  the
Institutional  Plus  Shares of the Fund for the thirty days ended  December  31,
1999 was 1.13%. The average annual total return of the  Institutional  Shares of
the Fund* for one- and  five-year  periods  ended  December 31, 1999,  and since
inception  on July 31, 1990 was 21.17%,  28.65% and  19.10%,  respectively.  The
average  annual total return of the  Institutional  Plus Shares of the Fund* for
the one-year period ended December 31, 1999, and since inception on July 7, 1997
was 21.21% and 23.08%, respectively.

- ---------
*The Fund reserves the right to deduct a transaction  fee from future  purchases
of shares.

AVERAGE ANNUAL TOTAL RETURN

Average annual total return is the average annual  compounded rate of return for
the  periods of one year,  five  years,  ten years or the life of the Fund,  all
ended on the last day of a recent month.  Average annual total return quotations
reflect  changes in the price of the Fund's shares and assume that all dividends
and capital gains distributions during the respective periods were reinvested in
Fund shares.  Average  annual total return is  calculated by finding the average
annual compounded rates of return of a hypothetical investment over such periods
according  to the  following  formula  (average  annual  total  return  is  then
expressed as a percentage):

                               T = (ERV/P)(1/N)-1

  Where:

          T   = average annual total return
          P   = a hypothetical  initial investment of $1,000
          n   = number of years
          ERV = ending  redeemable  value:  ERV is the value, at the end of the
                applicable period, of a hypothetical $1,000 investment made at
                the beginning of the applicable period.

                                      B-13
<PAGE>

AVERAGE ANNUAL AFTER-TAX TOTAL RETURN QUOTATION

We calculate the Fund's  average  annual  after-tax  total return by finding the
average annual  compounded  rate of return over the 1-, 5-, and 10-year  periods
(or for periods of the Fund's  operations)  that would equate the initial amount
invested to the after-tax value, according to the following formulas:

After-tax return:

                                 P(1+T)(N) = ATV

  Where:

          P   = a  hypothetical initial payment of $1,000
          T   = average annual after-tax total return
          n   = number of years
          ATV = after-tax value at the end of the 1-,5-, or 10-year periods of a
                hypothetical $1,000 payment made at the beginning of the time
                period, assuming no liquidation of the investment at the end of
                the measurement periods.

Instructions:

1.   Assume all distributions by the Fund are  reinvested--less the taxes due on
     such  distributions--at  the price on the  reinvestment  dates  during  the
     period.  Adjustments  may be made for  subsequent  re-characterizations  of
     distributions.

2.   Calculate  the  taxes  due on  distributions  by the Fund by  applying  the
     highest federal  marginal tax rates to each component of the  distributions
     on the reinvestment date (e.g.,  ordinary income,  short-term capital gain,
     long-term  capital gain,  etc.).  For periods after  December 31, 1997, the
     federal marginal tax rates used for the calculations are 39.6% for ordinary
     income and  short-term  capital gains and 20% for long-term  capital gains.
     Note that the  applicable tax rates may vary over the  measurement  period.
     Assume no taxes are due on the portions of any distributions  classified as
     exempt  interest  or  non-taxable  (i.e.  return of  capital).  Ignore  any
     potential tax liabilities other than federal tax liabilities  (e.g.,  state
     and local taxes).

3.   Include all recurring  fees that are charged to all  shareholder  accounts.
     For any  account  fees that vary  with the size of the  account,  assume an
     account size equal to the Fund's mean (or median) account size. Assume that
     no  additional  taxes or tax credits  result from any  redemption of shares
     required to pay such fees.

4.   State the total return quotation to the nearest hundreth of one percent.

CUMULATIVE TOTAL RETURN

Cumulative  total  return is the  cumulative  rate of  return on a  hypothetical
initial  investment of $1,000 for a specified  period.  Cumulative  total return
quotations reflect changes in the price of the Fund's shares and assume that all
dividends and capital gains  distributions  during the period were reinvested in
Fund shares.  Cumulative  total return is calculated  by finding the  cumulative
rates of a return of a hypothetical  investment over such periods,  according to
the  following  formula   (cumulative  total  return  is  then  expressed  as  a
percentage):

                                  C = (ERV/P)-1

  Where:

          C   = cumulative total return
          P   = a hypothetical initial investment of $1,000
          ERV = ending redeemable value: ERV is the value, at the end of the
                applicable period, of a hypothetical $1,000 investment made at
                the beginning of the applicable period.

                                      B-14
<PAGE>

SEC YIELDS

Yield is the net  annualized  yield based on a  specified  30-day (or one month)
period  assuming  semiannual  compounding  of  income.  Yield is  calculated  by
dividing the net  investment  income per share  earned  during the period by the
maximum offering price per share on the last day of the period, according to the
following formula:

                          YIELD = 2[((A-B)/CD+1)(6)-1]

  Where:

          a  = dividends and interest earned during the period.
          b  = expenses accrued for the period (net of reimbursements).
          c  = the average daily number of shares outstanding during the
               period that were entitled to receive dividends.
          d  = the maximum offering price per share on the last day of the
               period.


                              COMPARATIVE INDEXES

Vanguard may use reprinted  material  discussing The Vanguard Group, Inc. or any
of the member funds of The Vanguard Group of Investment Companies.

     Each of the investment  company members of The Vanguard Group, and Vanguard
Institutional Index Fund, may from time to time use one or more of the following
unmanaged indexes for comparative performance purposes.

STANDARD & POOR'S 500 COMPOSITE STOCK PRICE  INDEX--includes  stocks selected by
Standard & Poor's  Index  Committee  to  include  leading  companies  in leading
industries and to reflect the U.S. stock market.

STANDARD & POOR'S 500/BARRA VALUE  INDEX--consists of the stocks in the Standard
and  Poor's  500  Composite  Stock  Price  Index  ("S&P  500")  with the  lowest
price-to-book  ratios,  comprising 50% of the market  capitalization  of the S&P
500.

STANDARD & POOR'S 500/BARRA GROWTH  INDEX--consists of the stocks in the S&P 500
Index  with the  highest  price-to-book  ratios,  comprising  50% of the  market
capitalization of the S&P 500.

STANDARD &  POOR'S/MIDCAP  400 INDEX--is  composed of 400 medium sized  domestic
stocks.

STANDARD & POOR'S  SMALLCAP  600/BARRA VALUE  INDEX--contains  stocks of the S&P
SmallCap 600 Index which have a lower than average price-to-book ratio.

STANDARD & POOR'S SMALLCAP  600/BARRA GROWTH  INDEX--contains  stocks of the S&P
SmallCap 600 Index which have a higher than average price-to-book ratio.

RUSSELL  1000  VALUE  INDEX--consists  of the stocks in the  Russell  1000 Index
(comprising  the 1,000  largest  U.S.-based  companies  measured by total market
capitalization)  with the lowest  price-to-book  ratios,  comprising  50% of the
market capitalization of the Russell 1000.


WILSHIRE  5000 TOTAL MARKET  INDEX--consists  of more than 7,000  common  equity
securities,  covering  all  stocks  in the  U.S.  for  which  daily  pricing  is
available.

WILSHIRE  4500  COMPLETION  INDEX--consists  of all stocks in the Wilshire  5000
except for the 500 stocks in the Standard & Poor's 500 Index.


RUSSELL   2000  STOCK   INDEX--is   composed   of   approximately   2,000  small
capitalization stocks.

MORGAN  STANLEY  CAPITAL  INTERNATIONAL  EAFE  INDEX--is an  arithmetic,  market
value-weighted  average of the performance of over 900 securities  listed on the
stock exchanges of countries in Europe, Australasia and the Far East.

GOLDMAN SACHS 100  CONVERTIBLE  BOND  INDEX--currently  includes 71 bonds and 29
preferreds.   The  original  list  of  names  was  generated  by  screening  for
convertible  issues of $100  million or greater  in market  capitalization.  The
index is priced monthly.

SALOMON BROTHERS GNMA  INDEX--includes  pools of mortgages originated by private
lenders and guaranteed by the mortgage pools of the Government National Mortgage
Association.

                                      B-15
<PAGE>

SALOMON BROTHERS HIGH-GRADE  CORPORATE BOND  INDEX--consists of publicly issued,
non-convertible  corporate bonds rated Aa or Aaa. It is a value-weighted,  total
return index, including  approximately 800 issues with maturities of 12 years or
greater.

SALOMON BROTHERS BROAD  INVESTMENT-GRADE  BOND INDEX--is a market-weighted index
that contains approximately 4,700 individually priced investment-grade corporate
bonds rated BBB or better, U.S. Treasury/agency issues and mortgage pass-through
securities.


LEHMAN BROTHERS  LONG-TERM  TREASURY BOND INDEX--is a market weighted index that
contains  individually  priced U.S.  Treasury  securities  with maturities of 10
years or greater.


MERRILL LYNCH  CORPORATE & GOVERNMENT  BOND  INDEX--consists  of over 4,500 U.S.
Treasury, agency and investment grade corporate bonds.


LEHMAN BROTHERS  CORPORATE (BAA) BOND INDEX--all  publicly  offered  fixed-rate,
non-convertible  domestic corporate bonds rated Baa by Moody's,  with a maturity
longer  than 1 year and with more  than $100  million  outstanding.  This  index
includes over 1,500 issues.


BOND BUYER  MUNICIPAL BOND INDEX--is a yield index on current coupon  high-grade
general obligation municipal bonds.

STANDARD & POOR'S PREFERRED INDEX--is a yield index based upon the average yield
of four high-grade, non-callable preferred stock issues.

NASDAQ INDUSTRIAL INDEX--is composed of more than 3,000 industrial issues. It is
a  value-weighted  index  calculated  on price  change only and does not include
income.

COMPOSITE INDEX--70% Standard & Poor's 500 Index, 30% NASDAQ Industrial Index.


COMPOSITE  INDEX--65%  Standard  & Poor's  500  Index  and 35%  Lehman  Brothers
Corporate A or Better Bond Index.

COMPOSITE INDEX--65% Lehman Brothers Long-Term Corporate AA or Better Bond Index
and a 35% weighting in a blended  equity  composite (75% Standard & Poor's/BARRA
Value Index,  12.5%  Standard & Poor's  Utilities  Index and 12.5%  Standard and
Poor's Telephone Index).

LEHMAN BROTHERS  LONG-TERM  CORPORATE AA OR BETTER BOND  INDEX--consists  of all
publicly    issued,    fixed    rate,    non-convertible    investment    grade,
dollar-denominated, SEC-registered corporate debt rated AA or AAA.


LEHMAN  BROTHERS  AGGREGATE BOND INDEX--is a market weighted index that contains
individually priced U.S. Treasury,  agency, corporate, and mortgage pass-through
securities  corporate rated BBB- or better. The Index has a market value of over
$5 trillion.


LEHMAN  BROTHERS  CORPORATE A OR BETTER  BOND  INDEX--consists  of all  publicly
issued,  investment  grade  corporate  bonds rated A or better,  of all maturity
levels.


LEHMAN BROTHERS MUTUAL FUND SHORT (1-5) GOVERNMENT/CORPORATE  INDEX--is a market
weighted index that contains  individually  priced U.S.  Treasury,  agency,  and
corporate  investment grade bonds rated BBB- or better with maturities between 1
and 5 years. The index has a market value of over $1.6 trillion.

LEHMAN BROTHERS MUTUAL FUND INTERMEDIATE (5-10) GOVERNMENT/CORPORATE INDEX--is a
market weighted index that contains  individually priced U.S. Treasury,  agency,
and corporate  securities rated BBB- or better with maturities  between 5 and 10
years. The index has a market value of over $800 billion.

LEHMAN  BROTHERS  LONG (10+)  GOVERNMENT/CORPORATE  INDEX--is a market  weighted
index that contains  individually  priced U.S.  Treasury,  agency, and corporate
securities rated BBB- or better with maturities greater than 10 years. The index
has a market value of over $1.1 trillion.

                                                 SAI094-INSTITUTIONAL INDEX FUND

                                      B-16
<PAGE>

                                     PART C

                        VANGUARD INSTITUTIONAL INDEX FUND
                                OTHER INFORMATION

ITEM 23. EXHIBITS

EXHIBITS   DESCRIPTION
- --------   -----------
(a)        Declaration of Trust*
(b)        By-Laws*
(c)        Reference is made to Articles III and V of the Registrant's
           Declaration of Trust
(d)        Not applicable
(e)        Not applicable
(f)        Reference is made to the section entitled "Management of the Fund"
           in the Registrant's Statement of Additional Information
(g)        Custodian Agreement*
(h)        Amended and Restated Funds' Service Agreement*
(i)        Legal Opinion*

(j)        Consent of Independent Accountants+

(k)        Not Applicable
(l)        Not Applicable
(m)        Not Applicable
(n)        Not Applicable
(o)        Rule 18f-3 Plan*

(p)        Code of Ethics+

 -----------------
 *Filed previously
 +Filed herewith

ITEM 24. PERSONS CONTROLLED BY OR UNDER COMMON CONTROL WITH REGISTRANT

Registrant is not controlled by or under common control with any person.

ITEM 25. INDEMNIFICATION

The  Registrant's   organizational  documents  contain  provisions  indemnifying
Trustees and officers  against  liability  incurred in their official  capacity.
Article VII,  Section 2 of the Declaration of Trust provides that the Registrant
may  indemnify  and hold  harmless  each and every  Trustee and officer from and
against  any and all  claims,  demands,  costs,  losses,  expenses,  and damages
whatsoever  arising out of or related to the performance of his or her duties as
a Trustee or officer.  However,  this  provision does not cover any liability to
which a Trustee  or  officer  would  otherwise  be  subject by reason of willful
misfeasance,  bad faith,  gross negligence,  or reckless disregard of the duties
involved  in  the  conduct  of  his or her  office.  Article  VI of the  By-Laws
generally provides that the Registrant shall indemnify its Trustees and officers
from  any  liability  arising  out of  their  past or  present  service  in that
capacity.  Among other things,  this provision excludes any liability arising by
reason of willful  misfeasance,  bad faith,  gross  negligence,  or the reckless
disregard  of the duties  involved in the conduct of the  Trustee's or officer's
office with the Registrant.

ITEM 26. BUSINESS AND OTHER CONNECTIONS OF INVESTMENT ADVISER

Investment  advisory  services  are provided to the  Registrant  by The Vanguard
Group,  Inc., a  jointly-owned  subsidiary of the funds in the Vanguard Group of
Investment  Companies.  See the information  concerning The Vanguard Group, Inc.
set forth in Parts A and B. For information as to any other  business,  vocation
or employment  of a  substantial  nature in which each trustee or officer of the
Registrant's investment advisor is or has been engaged for his own account or in
the capacity of officer, employee, partner or trustee, reference is made to Form
ADV (File #801-11953) filed by it under the Investment Advisers Act of 1940.

                                      C-1
<PAGE>

ITEM 27. PRINCIPAL UNDERWRITERS

a.     Not Applicable
b.     Not Applicable
c.     Not Applicable

ITEM 28. LOCATION OF ACCOUNTS AND RECORDS

The books,  accounts  and other  documents  required by Section  31(a) under the
Investment  Company  Act of 1940 and the rules  promulgated  thereunder  will be
maintained  in the physical  possession  of  Registrant;  Registrant's  Transfer
Agent, The Vanguard Group, Inc., 100 Vanguard Boulevard,  Malvern,  Pennsylvania
19355; and the Registrant's  Custodian,  First Union National Bank,  PA4943, 530
Walnut Street, Philadelphia, PA 19106.


ITEM 29. MANAGEMENT SERVICES

Other than as set forth under the description of The Vanguard Group in Part B of
this   Registration   Statement,   the   Registrant   is  not  a  party  to  any
management-related service contract.

ITEM 30. UNDERTAKINGS

Not Applicable


                                      C-2
<PAGE>

                                   SIGNATURES

Pursuant to the  requirements  of the  Securities Act of 1933 and the Investment
Company  Act of  1940,  the  Registrant  hereby  certifies  that  it  meets  all
requirements for effectiveness of this Registration  Statement  pursuant to Rule
485(b) under the Securities Act of 1933 and has duly caused this  Post-Effective
Amendment  to this  Registration  Statement  to be signed  on its  behalf by the
undersigned,  thereunto  duly  authorized,  in the Town of Valley  Forge and the
Commonwealth of Pennsylvania, on the 6th day of April, 2000.


                                               VANGUARD INSTITUTIONAL INDEX FUND
                                            BY:_________________________________
                                                          (signature)
                                                         (HEIDI STAM)
                                                       JOHN J. BRENNAN*
                                            CHAIRMAN AND CHIEF EXECUTIVE OFFICER

     Pursuant  to  the   requirements  of  the  Securities  Act  of  1933,  this
Post-Effective  Amendment to the Registration Statement has been signed below by
the following persons in the capacities and on the date indicated:


SIGNATURE                     TITLE                           DATE
- --------------------------------------------------------------------------------

By:/S/ JOHN J. BRENNAN        President, Chairman, Chief      April 6, 2000
   ---------------------------  Executive Officer, and Trustee
       (Heidi Stam)
      John J. Brennan*


By:/S/ JOANN HEFFERNAN HEISEN Trustee                         April 6, 2000
   ---------------------------
       (Heidi Stam)
     JoAnn Heffernan Heisen*


By:/S/ BRUCE K. MACLAURY      Trustee                         April 6, 2000
   ---------------------------
       (Heidi Stam)
      Bruce K. MacLaury*


By:/S/ BURTON G. MALKIEL      Trustee                         April 6, 2000
   ---------------------------
       (Heidi Stam)
       Burton G. Malkiel*


By:/S/ ALFRED M. RANKIN, JR.  Trustee                         April 6, 2000
   ---------------------------
       (Heidi Stam)
     Alfred M. Rankin, Jr.*


By:/S/ JOHN C. SAWHILL        Trustee                         April 6, 2000
   ---------------------------
       (Heidi Stam)
      John C. Sawhill*


By:/S/ JAMES O. WELCH, JR.    Trustee                         April 6, 2000
   ---------------------------
       (Heidi Stam)
     James O. Welch, Jr.*


By:/S/ J. LAWRENCE WILSON     Trustee                         April 6, 2000
   ---------------------------
       (Heidi Stam)
     J. Lawrence Wilson*


By:/S/ THOMAS J. HIGGINS      Treasurer and Principal         April 6, 2000
   ---------------------------  Financial Officer and
       (Heidi Stam)             Principal Accounting Officer
      Thomas J. Higgins*

*By Power of  Attorney.  See File Number  33-4424,  filed on January  25,  1999.
 Incorporated by Reference.
<PAGE>

                                  EXHIBIT INDEX


Consent of Independent Accountants .................................... EX-99.BJ
Code of Ethics ........................................................ EX-99.BP



<PAGE>

                       CONSENT OF INDEPENDENT ACCOUNTANTS

We hereby  consent to the  incorporation  by  reference  in the  Prospectus  and
Statement of Additional  Information  constituting parts of this  Post-Effective
Amendment No. 19 to the Registration  Statement on Form N-1A (the  "Registration
Statement")  of our report  dated  February 2, 2000,  relating to the  financial
statements  and financial  highlights  appearing in the December 31, 1999 Annual
Report to  Shareholders  of Vanguard  Institutional  Index Fund,  which are also
incorporated by reference into the  Registration  Statement.  We also consent to
the references to us under the heading "Financial  Highlights" in the Prospectus
and    under    the    headings    "Financial     Statements"    and    "Service
Providers--Independent Accountants" in the Statement of Additional Information.

PricewaterhouseCoopers LLP
Philadelphia, PA


April 5, 2000


<PAGE>


                            THE VANGUARD GROUP, INC.
                            ------------------------

                                 CODE OF ETHICS
                                 --------------

SECTION 1:  BACKGROUND

This Code of Ethics has been  approved  and adopted by the Board of Directors of
The Vanguard Group, Inc.  ("Vanguard") and the Boards of Trustees of each of the
Vanguard funds in compliance with Rule 17j-1 under the Investment Company Act of
1940. The Code has been amended and restated effective as of May 1, 1999. Except
as otherwise provided,  the Code applies to all "Vanguard personnel," which term
includes all  employees,  officers,  Directors  and Trustees of Vanguard and the
Vanguard funds. The Code also contains  provisions which apply to the investment
advisers to the Vanguard funds (see section 11).

SECTION 2:  STATEMENT OF GENERAL FIDUCIARY STANDARDS

This Code of Ethics is based on the overriding principle that Vanguard personnel
act  as  fiduciaries  for  shareholders'  investments  in  the  Vanguard  funds.
Accordingly,  Vanguard  personnel must conduct their  activities at all times in
accordance with the following standards:

     a)   SHAREHOLDERS' INTERESTS COME FIRST. In the course of fulfilling  their
duties and  responsibilities  to Vanguard fund shareholders,  Vanguard personnel
must at all times place the interests of Vanguard fund  shareholders  first.  In
particular,  Vanguard  personnel must avoid serving their own personal interests
ahead of the interests of Vanguard fund shareholders.

     b)   CONFLICTS OF INTEREST  MUST BE AVOIDED. Vanguard  personnel must avoid
any situation  involving an actual or potential conflict of interest or possible
impropriety with respect to their duties and  responsibilities  to Vanguard fund
shareholders.

     c)   COMPROMISING  SITUATIONS MUST BE AVOIDED. Vanguard  personnel must not
take  advantage  of their  position  of trust and  responsibility  at  Vanguard.
Vanguard  personnel must avoid any situation that might  compromise or call into
question  their exercise of full  independent  judgment in the best interests of
Vanguard fund shareholders.
<PAGE>

All  activities  of Vanguard  personnel  should be guided by and adhere to these
fiduciary  standards.  The remainder of this Code sets forth  specific rules and
procedures  which are consistent with these fiduciary  standards.  However,  all
activities by Vanguard  personnel  are required to conform with these  fiduciary
standards  regardless  of whether the activity is  specifically  covered in this
Code.

SECTION 3:  DUTY OF CONFIDENTIALITY

Vanguard personnel must keep confidential at all times any nonpublic information
they may obtain in the course of their employment at Vanguard.  This information
includes but is not limited to:

     1)   information  on the  vanguard  funds,  including  recent or  impending
          securities    transactions   by   the   funds,   activities   of   the
          funds' advisers, offerings of new funds, and closings of funds;

     2)   information   on   Vanguard   fund    shareholders   and   prospective
          shareholders,  including their  identities,  investments,  and account
          transactions;

     3)   information  on  other  vanguard   personnel,   including  their  pay,
          benefits, position level, and performance ratings; and

     4)   information on Vanguard business  activities,  including new services,
          products, technologies, and business initiatives.

Vanguard  personnel  have  the  highest  fiduciary   obligation  not  to  reveal
confidential  Vanguard  information  to any party that does not have a clear and
compelling need to know such information.

SECTION 4:  GIFT POLICY

Vanguard  personnel are prohibited  from seeking or accepting  gifts of material
value from any person or entity,  including  any Vanguard  fund  shareholder  or
Vanguard client,  when such gift is in relation to doing business with Vanguard.
In certain  cases,  Vanguard  PERSONNEL MAY ACCEPT GIFTS OF DE MINIMIS value (as
determined in accordance with guidelines set forth in Vanguard's Human Resources
Policy Manual) but only if they obtain the approval of a Vanguard officer.
<PAGE>

SECTION 5:  OUTSIDE ACTIVITIES

     a)   PROHIBITIONS   ON   SECONDARY   EMPLOYMENT.    Vanguard employees  are
prohibited from working for any business or enterprise in the financial services
industry  that  competes  with  Vanguard.  In addition,  Vanguard  employees are
prohibited from working for any  organization  that could possibly  benefit from
the  employee's  knowledge of  confidential  Vanguard  information,  such as new
Vanguard  services  and  technologies.   Beyond  these  prohibitions,   Vanguard
employees may accept secondary employment, but only with prior approval from the
Vanguard Compliance Department.  Vanguard officers are prohibited from accepting
or  serving  in any form of  secondary  employment  unless  they  have  received
approval from a Vanguard  Managing  Director or the Vanguard  Chairman and Chief
Executive Officer.

     b)   PROHIBITION  ON  SERVICE  AS  DIRECTOR  OR PUBLIC  OFFICIAL.  Vanguard
officers and employees are prohibited  from serving on the board of directors of
any publicly traded company or in an official  capacity for any federal,  state,
or local government (or governmental  agency or  instrumentality)  without prior
approval from the Vanguard Compliance Department.

     c)   PROHIBITION ON MISUSE OF VANGUARD TIME OR PROPERTY. Vanguard personnel
are  prohibited  from using  Vanguard time,  equipment,  services,  personnel or
property  for any  purposes  other  than the  performance  of their  duties  and
responsibilities at Vanguard.

SECTION 6:  GENERAL PROHIBITIONS ON TRADING

     a)   TRADING  ON  KNOWLEDGE  OF  VANGUARD  FUNDS  ACTIVITIES. All  Vanguard
personnel are prohibited  from taking  personal  advantage of their knowledge of
recent or impending  securities  activities of the Vanguard  funds or the funds'
investment  advisers.  In particular,  Vanguard  personnel are  prohibited  from
purchasing  or selling,  directly or  indirectly,  any  security  when they have
actual knowledge that the security is being purchased or sold, or considered for
purchase or sale, by a Vanguard fund. This prohibition applies to all securities
in which the person has acquired or will  acquire  "beneficial  ownership."  For
these  purposes,  a person is  considered  to have  beneficial  ownership in all
securities  over  which  the  person  enjoys  economic  benefits   substantially
equivalent to ownership (for example,  securities held in trust for the person's
benefit),  regardless of who is the registered owner. Under this Code of Ethics,
Vanguard personnel are considered to have beneficial ownership of all securities
owned by their spouse or minor children.
<PAGE>

     b)   VANGUARD INSIDER TRADING POLICY.  All Vanguard  personnel are  subject
to Vanguard's  Insider Trading  Policy,  which is considered an integral part of
this Code of  Ethics.  Vanguard's  Insider  Trading  Policy  prohibits  Vanguard
personnel  from  buying or  selling  any  security  while in the  possession  of
material nonpublic information about the issuer of the security. The policy also
prohibits  Vanguard  personnel from  communicating to third parties any material
nonpublic information about any security or issuer of securities.  Any violation
of Vanguard's Insider Trading Policy may result in penalties which could include
termination of employment with Vanguard.

SECTION 7:  ADDITIONAL TRADING RESTRICTIONS FOR ACCESS PERSONS

     a)   APPLICATION. The  restrictions of this section 7 apply to all Vanguard
access persons. For purposes of the Code of Ethics, "access persons" include:

     1)   any  Director  or Trustee of Vanguard  or a Vanguard  fund,  excluding
          disinterested  Directors and Trustees  (i.e.,  any Director or Trustee
          who is not an  "interested  person"  of a  Vanguard  fund  within  the
          meaning of Section 2(a)(19) of the Investment Company Act of 1940);

     2)   any officer of Vanguard or a Vanguard fund; and

     3)   any  employee of Vanguard or a Vanguard  fund who in the course of his
          or her regular  duties  participates  in the  selection  of a Vanguard
          fund's  securities or who works in a Vanguard  department or unit that
          has  access to  information  regarding  a  Vanguard  fund's  impending
          purchases or sales of securities.

The  Vanguard  Compliance  Department  will notify all  Vanguard  personnel  who
qualify as access persons of their duties and  responsibilities  under this Code
of Ethics. The restrictions of this section 7 apply to all transactions in which
a Vanguard access person has or will acquire  beneficial  ownership (see section
6a) of a security,  including  transactions by a spouse or minor child. However,
the restrictions do not apply to transactions involving:  (i) direct obligations
of the  Government  of the United  States;  (ii) high  quality  short-term  debt
instruments,  including  bankers'  acceptances,  bank  certificates  of deposit,
commercial  paper,  and  repurchase  agreements;  and (iii) shares of registered
open-end  investment  companies  (including  shares of
<PAGE>

any Vanguard fund). In addition,  the  restrictions do not apply to transactions
in accounts  over which the access  person has no direct or indirect  control or
influence.

     b)   GENERAL  RESTRICTIONS FOR ACCESS PERSONS.  Vanguard access persons are
subject  to  the  following   restrictions  with  respect  to  their  securities
transactions:

     1)   PRE-CLEARANCE OF SECURITIES TRANSACTIONS. Vanguard access persons must
          receive  approval  from  the  Vanguard  Compliance  Department  before
          purchasing  or  selling  any  securities.   The  Vanguard   Compliance
          Department  will  notify  Vanguard  access  persons if their  proposed
          securities transactions are permitted under this Code of Ethics.

     2)   TRADING THROUGH VANGUARD BROKERAGE  SERVICES.  Vanguard access persons
          must  conduct  all  their  securities  transactions  through  Vanguard
          Brokerage   Services.   Vanguard   Brokerage   Services  will  send  a
          confirmation  notice  of any  purchase  or  sale  of  securities  by a
          Vanguard access person to the Vanguard Compliance Department.

     3)   PROHIBITION ON INITIAL PUBLIC  OFFERINGS.  Vanguard access persons are
          prohibited from acquiring securities in an initial public offering.

     4)   PROHIBITION  ON  PRIVATE  PLACEMENTS.   Vanguard  access  persons  are
          prohibited from acquiring  securities in a private  placement  without
          prior approval from the Vanguard Compliance  Department.  In the event
          an access person receives approval to purchase securities in a private
          placement,  the access person must  disclose that  investment if he or
          she plays any part in a  Vanguard  fund's  later  consideration  of an
          investment in the issuer.

     5)   PROHIBITION ON OPTIONS.  Vanguard  access persons are prohibited  from
          acquiring or selling any option on any security.

     6)   PROHIBITION ON  SHORT-SELLING.  Vanguard access persons are prohibited
          from  selling  any  security  that the access  person  does not own or
          otherwise engaging in "short-selling" activities.

     7)   PROHIBITION ON SHORT-TERM TRADING PROFITS. Vanguard access persons are
          prohibited  from  profiting  in the  purchase  and  sale,  or sale and
          purchase, of the same (or related) securities within 60 calendar days.
          In the event that an access person realizes profits on
<PAGE>

          such short-term trades, the access person must relinquish such profits
          to The Vanguard Group Foundation.

     c)   BLACKOUT RESTRICTIONS FOR ACCESS PERSONS.  All Vanguard access persons
are subject to the  following  restrictions  when their  purchases  and sales of
securities coincide with trades by the Vanguard funds:

     1)   PURCHASES AND SALES WITHIN THREE DAYS FOLLOWING A FUND TRADE. Vanguard
          access persons are prohibited  from purchasing or selling any security
          within  three  calendar  days after a Vanguard  fund has traded in the
          same (or a related) security. In the event that an access person makes
          a prohibited  purchase or sale within the three-day period, the access
          person must unwind the  transaction  and  relinquish any gain from the
          transaction to The Vanguard Group Foundation.

     2)   PURCHASES WITHIN SEVEN DAYS BEFORE A FUND PURCHASE.  A Vanguard access
          person who  purchases a security  within seven  calendar days before a
          Vanguard fund purchases the same (or a related) security is prohibited
          from  selling the security  for a period of six months  following  the
          fund's  trade.  In the event that an access  person makes a prohibited
          sale within the six-month period, the access person must relinquish to
          The Vanguard Group Foundation any gain from the transaction.

     3)   SALES WITHIN SEVEN DAYS BEFORE A FUND SALE. A Vanguard  access  person
          who sells a security  within  seven days before a Vanguard  fund sells
          the same (or a related) security must relinquish to The Vanguard Group
          Foundation the difference  between the access  person's sale price and
          the Vanguard  fund's sale price  (assuming  the access  person's  sale
          price is higher).

     4)   RESTRICTIONS  NOT  APPLICABLE TO TRADES BY VANGUARD  INDEX FUNDS.  The
          restrictions of this section 7c do not apply to purchases and sales of
          securities by Vanguard  access persons which would  otherwise  violate
          section 7c solely because the transactions coincide with trades by any
          Vanguard index funds.

SECTION 8:  ADDITIONAL TRADING RESTRICTIONS FOR INSTITUTIONAL CLIENT CONTACTS
<PAGE>

     a)   APPLICATION.  The restrictions of this section 8 apply to all Vanguard
Institutional  client  contacts.   For  purposes  of  the  Code  of  Ethics,  an
"Institutional  client  contact"  includes any Vanguard  employee who works in a
department or unit at Vanguard that has  significant  levels of  interaction  or
dealings with the  management of clients of  Vanguard's  Institutional  Investor
Group.  The Vanguard  Compliance  Department will notify Vanguard  employees who
qualify as Institutional client contacts of the restrictions of this Section 8.

     b)   PROHIBITION ON TRADING  SECURITIES OF  INSTITUTIONAL CLIENTS. Vanguard
Institutional client contacts are prohibited from acquiring securities issued by
clients of the Vanguard  Institutional  Investor Group (including any options or
futures  contracts based on such  securities).  In the event that any individual
who  becomes  subject to this  prohibition  already  owns  securities  issued by
Institutional clients, the individual will be prohibited from disposing of those
securities without prior approval from the Vanguard Compliance  Department.  The
restrictions of this section 8 apply to all transactions in which  Institutional
client contacts have acquired or would acquire beneficial ownership (see section
6a) of a security,  including  transactions by a spouse or minor child. However,
the  restrictions  do not apply to  transactions  in any  account  over which an
individual  does not possess any direct or indirect  control or  influence.  The
Vanguard Compliance Department will maintain a list of the Institutional clients
to which the  prohibitions  of this  section 8 apply.  The  Vanguard  Compliance
Department may waive the  prohibition on acquiring  securities of  Institutional
clients  in  appropriate  cases  (including,  for  example,  cases  in  which an
individual  acquires  securities  as  part  of  an  inheritance  or  through  an
employer-sponsored employee benefits or compensation program).

SECTION 9:  COMPLIANCE PROCEDURES

     a)   APPLICATION. The  requirements of this section 9 apply to all Vanguard
personnel other than disinterested  Directors and Trustees (see section 7a). The
requirements apply to all transactions in which Vanguard personnel have acquired
or would acquire beneficial ownership (see section 6a) of a security,  including
transactions by a spouse or minor child.  However, the requirements do not apply
to  transactions  involving:  (i) direct  obligations  of the  Government of the
United States; (ii) high quality short-term debt instruments, including bankers'
acceptances,  bank  certificates of deposit,  commercial  paper,  and repurchase
agreements;  and  (iii)  shares  of  registered  open-end  investment  companies
(including  shares of any Vanguard fund). In addition,  the  requirements do not
apply to securities acquired for accounts over which the person has no direct or
indirect control or influence.
<PAGE>

     b)   DISCLOSURE OF PERSONAL HOLDINGS. All Vanguard  personnel must disclose
their personal securities  holdings to the Vanguard  Compliance  Department upon
commencement of employment with Vanguard.  These  disclosures  must identify the
title,  number of shares,  and  principal  amount with respect to each  security
holding.

     c)   RECORDS OF SECURITIES TRANSACTIONS. All Vanguard personnel must notify
the  Vanguard  Compliance  Department  if they  have  opened or intend to open a
brokerage  account.  Vanguard  personnel must direct their brokers to supply the
Vanguard Compliance Department with duplicate  confirmation  statements of their
securities  transactions  and  copies  of  all  periodic  statements  for  their
brokerage accounts.

     d)   CERTIFICATION  OF  COMPLIANCE.  All  Vanguard  personnel  must certify
annually to the  Vanguard  Compliance  Department  that:  (i) they have read and
understand this Code of Ethics; (ii) they have complied with all requirements of
the Code of Ethics;  and (3) they have reported all transactions  required to be
reported under the Code of Ethics.

SECTION 10:  REQUIRED REPORTS BY DISINTERESTED DIRECTORS AND TRUSTEES

Disinterested  Directors  and  Trustees  (see section 7a) are required to report
their  securities  transactions  to the Vanguard  Compliance  Department only in
cases where the  Director or Trustee knew or should have known during the 15-day
period  immediately  preceding or following the date of the transaction that the
security had been  purchased or sold,  or was being  considered  for purchase or
sale, by a Vanguard fund.

SECTION 11: APPLICATION TO INVESTMENT ADVISERS

     a)   ADOPTION OF CODE OF ETHICS. Each investment adviser to a Vanguard fund
must  adopt a code of  ethics in  compliance  with Rule  17j-1 and  provide  the
Vanguard  Compliance  Department  with a copy  of the  code  of  ethics  and any
subsequent amendments.  Each investment adviser is responsible for enforcing its
code of ethics and reporting to the Vanguard  Compliance  Department on a timely
basis any violations of the code of ethics and resulting sanctions.
<PAGE>

     b)   PREPARATION OF ANNUAL  REPORTS.  Each investment adviser to a Vanguard
fund must prepare an annual report on its code of ethics for review by the Board
of Trustees of the Vanguard fund. This report must contain the following:

     1)   a description of any issues arising under the adviser's code of ethics
          including, but not limited to, information about any violations of the
          code,  sanctions imposed in response to such violations,  changes made
          to the code's provisions or procedures, and any recommended changes to
          the code; and

     2)   a  certification   that  the  investment   adviser  has  adopted  such
          procedures as are reasonably  necessary to prevent access persons from
          violating the code of ethics.

SECTION 12:  REVIEW BY BOARDS OF DIRECTORS AND TRUSTEES

     a)   REVIEW OF INVESTMENT ADVISERS'  CODE OF ETHICS. Prior to retaining the
services of any investment adviser for a Vanguard fund, the Board of Trustees of
the  Vanguard  fund must  review the code of ethics  adopted  by the  investment
adviser  pursuant to Rule 17j-1 under the  Investment  Company Act of 1940.  The
Board of Trustees must receive a certification  from the investment adviser that
the adviser has adopted such  procedures as are reasonably  necessary to prevent
access persons from  violating the adviser's  code of ethics.  A majority of the
Trustees  of the  Vanguard  fund,  including  a  majority  of the  disinterested
Trustees  of the Fund,  must  determine  whether  the  adviser's  code of ethics
contains such  provisions as are reasonably  necessary to prevent access persons
from  engaging  in any act,  practice,  or course of conduct  prohibited  by the
anti-fraud provisions of Rule 17j-1.

     b)   REVIEW OF VANGUARD ANNUAL REPORTS. The Vanguard Compliance  Department
must prepare an annual  report on this Code of Ethics for review by the Board of
Directors  of Vanguard  and the Boards of Trustees of the  Vanguard  funds.  The
report must contain the following:

     1)   a  description  of issues  arising  under the Code of Ethics since the
          last  report  including,  but not limited  to,  information  about any
          violations  of  the  Code,  sanctions  imposed  in  response  to  such
          violations,  changes made to the Code's provisions or procedures,  and
          any recommended changes to the Code; and
<PAGE>

     2)   a certification that Vanguard and the Vanguard Funds have adopted such
          procedures as are reasonably  necessary to prevent access persons from
          violating the Code of Ethics.

SECTION 13:  SANCTIONS

In the event of any violation of this Code of Ethics, Vanguard senior management
will  impose  such  sanctions  as deemed  necessary  and  appropriate  under the
circumstances  and in the best interests of Vanguard fund  shareholders.  In the
case of any  violations  by Vanguard  employees,  the range of  sanctions  could
include a letter of censure,  suspension of employment without pay, or permanent
termination of employment.

SECTION 14:  RETENTION OF RECORDS

Vanguard must maintain all records required by Rule 17j-1 including:  (i) copies
of this Code of Ethics and the codes of ethics of all investment advisers to the
Vanguard  funds;  (ii)  records  of any  violations  of the codes of ethics  and
actions taken as a result of the violations;  (iii) copies of all certifications
made by Vanguard  personnel  pursuant to section 9d; (iv) lists of all  Vanguard
personnel  who are,  or within the past five years  have  been,  access  persons
subject  to the  trading  restrictions  of  section 8 and lists of the  Vanguard
compliance  personnel  responsible for monitoring  compliance with those trading
restrictions;  and (v) copies of the annual  reports to the Boards of  Directors
and Trustees pursuant to section 12.



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