Vanguard Bond Index Funds

Supplement Dated November 8, 2021, to the Statement of Additional Information Dated April 29, 2021

Important Changes to Vanguard Inflation-Protected Securities Fund

Effective immediately, John Madziyire has been added as a co-portfolio manager of Vanguard Inflation-Protected Securities Fund. The Fund's investment objective, strategies, and policies remain unchanged.

Statement of Additional InformationText Changes

In the Investment Advisory and Other Services section, the following text and table replace those under the sub-heading "1. Other Accounts Managed" on page B-49:

The following table provides information relating to the other accounts managed by the portfolio managers of the Funds as of the fiscal year ended December 31, 2020 (unless otherwise noted):

1 Includes Vanguard Intermediate-Term Bond Index Fund, Long-Term Bond Index Fund, Short-Term Bond Index Fund, Total Bond Market Index Fund, and Total Bond Market II Index Fund which collectively held assets of $639 billion as of December 31, 2020.

2 Includes Vanguard Inflation-Protected Securities Fund which held assets of $34 billion as of December 31, 2020.

3 Mr. Madziyire began co-managing Vanguard Inflation-Protected Securities Fund on November 8, 2021.

4 Information provided as of September 30, 2021, and includes Vanguard Inflation-Protected Securities Fund, which held assets of $39B as of September 30, 2021.

Within the same section, the following text is added under the sub-heading "4. Ownership of Securities" on page B-50:

As of September 30, 2021, Mr. Madziyire did not own any shares of Vanguard Inflation-Protected Securities.