January 24, 2013

U.S. Securities & Exchange Commission

100 F Street, N.E.

Washington, DC 20549

Re: Vanguard Institutional Index Funds (the “Trust”); File No. 33-34494

Commissioners:

Pursuant to Rule 497(e) under the Securities Act of 1933, we hereby file exhibits containing

interactive data format risk/return summary information that reflects the risk/return summary

information in the supplement dated January 15, 2013, filed pursuant to Rule 497(e), for Vanguard

Institutional Total Stock Market Index Fund, a series of the above mentioned Trust.

If you have any questions or comments concerning the foregoing, please contact me at

(610) 669-1955.

Sincerely,

Tara R. Buckley

Senior Counsel

The Vanguard Group, Inc.

Enclosures

cc: Chad Eskildsen, Esq.

U. S. Securities and Exchange Commission