[SHIP]
                            [THE VANGUARD GROUP LOGO]

                        VANGUARD(R) U.S. STOCK INDEX FUND

                SUPPLEMENT TO THE PROSPECTUS DATED APRIL 29, 2005

IMPORTANT INFORMATION ABOUT INSTITUTIONAL AND INSTITUTIONAL PLUS SHARES

Vanguard  is  pleased  to  announce   that  initial   investment   minimums  for
Institutional Shares have been lowered from $10 million to $5 million, effective
June 9, 2005,  except for Vanguard  Institutional  Total Stock Market Index Fund
Institutional  Shares,  whose minimum has been lowered from $200 million to $100
million. In addition,  the minimum for Vanguard Institutional Total Stock Market
Index Fund  Institutional Plus Shares has been lowered from $500 million to $200
million, effective, June 9, 2005.

All prospectus  references to the former investment  minimums are hereby changed
accordingly.  In addition,  the following changes are made to the INVESTING WITH
VANGUARD section of the prospectus.

The Buying Shares section is amended as follows:

ACCOUNT  MINIMUMS TO OPEN AND  MAINTAIN AN ACCOUNT.  $5 million,  except for the
Institutional  Plus Shares ($200 million) of Vanguard  Institutional  Index Fund
and the Institutional  Shares ($100 million) and Institutional Plus Shares ($200
million) of Vanguard Institutional Total Stock Market Index Fund.

Vanguard  institutional clients generally may meet the minimum investment amount
by aggregating up to three separate  accounts  within the Fund. This policy does
not apply to clients  receiving special  administrative  services from Vanguard,
nor  does  this  policy  apply  to  omnibus  accounts  maintained  by  financial
intermediaries.

The Converting Shares section is amended as follows:

CONVERSIONS FROM INVESTOR SHARES OR ADMIRAL(TM) SHARES
You are eligible for a self-directed  conversion from Investor Shares or Admiral
Shares into Institutional Shares of the same Fund (if available),  provided that
your account balance in the Fund is at least $5 million. Registered users of our
website,  www.vanguard.com,  may request a conversion online, or you may contact
Vanguard by telephone or by mail to request this transaction.

                                                                  (over, please)

CONVERSIONS FROM INSTITUTIONAL SHARES
You are eligible for a self-directed  conversion from Institutional  Shares into
Institutional  Plus Shares of the same Fund (if  available),  provided that your
account  balance  is at least $200  million.  Registered  users of our  website,
www.vanguard.com,  may request a conversion online, or your may contact Vanguard
by telephone or by mail to request this transaction.

MANDATORY CONVERSIONS INTO ANOTHER SHARE CLASS
If an investor no longer  meets the  requirements  for  Institutional  Shares or
Institutional  Plus Shares,  the Fund may  automatically  convert the investor's
shares into another share class,  as  appropriate.  A decline in the  investor's
account balance because of market movement may result in such a conversion.  The
Fund will notify the investor in writing  before any mandatory  conversion  into
another share class.


(C) 2005 The Vanguard Group, Inc. All rights reserved.
Vanguard Marketing Corporation, Distributor.                     PS854   062005