As filed with the U.S. Securities and Exchange Commission on December 8, 2021

File Nos. 333-179904 and 811-22649

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

(Check appropriate box or boxes)

iShares U.S. ETF Trust

(Exact Name of Registrant as Specified in Charter)

c/o BlackRock Fund Advisors

60 State Street

Boston, MA 02109

(Address of Principal Executive Office)(Zip Code)

Registrant’s Telephone Number, including Area Code: (415) 670-2000

The Corporation Trust Company

1209 Orange Street

Wilmington, DE 19801

(Name and Address of Agent for Service)

With Copies to:

It is proposed that this filing will become effective (check appropriate box):

If appropriate, check the following box:

Explanatory Note

This Post-Effective Amendment No. 616 to the Registrant’s Registration Statement on Form N-1A is being filed pursuant to paragraph (b)(1)(iii) of Rule 485 of the Securities Act of 1933, as amended (the “1933 Act”), solely for the purpose of delaying, until January 7, 2022, the effectiveness of the registration statement for the iShares Commodity Multi-Strategy ETF (the “Fund”), filed in Post-Effective Amendment No. 448 on December 3, 2018, pursuant to paragraph (a) of Rule 485 of the 1933 Act.

The effectiveness of the Registration Statement of the Fund was previously delayed pursuant to paragraph (b)(1)(iii) of Rule 485 of the 1933 Act as follows:

This Post-Effective Amendment No. 616 incorporates by reference the information contained in Parts A, B and C of Post-Effective Amendment No. 448.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all the requirements for the effectiveness of this Registration Statement pursuant to Rule 485(b)(1)(iii) of the Securities Act of 1933, as amended, and has duly caused this Post-Effective Amendment No. 616 to the Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of San Francisco and the State of California on the 8^th day of December, 2021.

iSHARES U.S. ETF TRUST 

Pursuant to the requirements of the Securities Act of 1933, as amended, this Post-Effective Amendment No. 616 to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated.