Form 485BXT VANGUARD FIXED INCOME

Explanatory Note

This Post-Effective Amendment No. 120 under the Securities Act of 1933, as amended (the “Securities Act”) (Amendment No. 121 under the Investment Company Act of 1940, as amended (the “1940 Act”)) to the registration statement on Form N-1A (the “Registration Statement”) of Vanguard Fixed Income Securities Funds (the “Trust”) is being filed pursuant to paragraph (b)(1)(iii) of Rule 485 under the Securities Act solely for the purpose of delaying, until May 24, 2018, the pending effective date of the Trust’s 118^th Post-Effective Amendment. By way of further background:

• Post-Effective Amendment No. 119 was filed under Rule 485(b)(1)(iii) on March 29, 2018, for the sole purpose of extending until May 24, 2018, the then-pending effective date of Post-Effective Amendment No. 118.
• Post-Effective Amendment No. 118 was filed under Rule 485(a)(1) on February 1, 2018, for the purposes of: (1) changing the name of Vanguard REIT II Index Fund to Vanguard Real Estate II
  Index Fund; (2) changing the Real Estate II Index Fund’s benchmark index; (3) disclosing a change to the Real Estate II Index Fund’s investment objective; and (4) effecting a number of non- material editorial changes. Post-Effective Amendment No. 118 originally requested that the Amendment become effective 60 days after filing pursuant to the requirements of Rule 485(a)(1).

This Post-Effective Amendment No. 120 incorporates by reference the information contained in Parts A, B, and C of Post-Effective Amendment No. 118 to the Trust’s Registration Statement.

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 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 this 27th day of April, 2018.

VANGUARD FIXED INCOME SECURITIES FUNDS

BY: /s/ Mortimer J. Buckley*

Mortimer J. Buckley
Chief Executive Officer, President, and Trustee

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:

*By: /s/ Anne E. Robinson

Anne E. Robinson, pursuant to a Power of Attorney filed on January 18, 2018, see File Number 33-32216, Incorporated by Reference.

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