UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of report (Date of earliest event reported): February 18, 2021 (February 17, 2021)

United States Steel Corporation

(Exact Name of Registrant as Specified in Charter)

600 Grant Street,

Pittsburgh, PA 15219-2800

(Address of Principal Executive Offices, and Zip Code)

(412) 433-1121

Registrant’s Telephone Number, Including Area Code

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2).

Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Item 7.01 Regulation FD Disclosure

In a press release issued on February 17, 2021, United States Steel Corporation (the “Company”) announced that, in connection with the Company’s recently completed offering of 42,000,000 shares of its common stock, the underwriter has exercised in full its option to purchase 6,300,000 additional shares of common stock (the “Additional Shares”). A copy of the press release is furnished as Exhibit 99.1 hereto.

On February 18, 2021, the Company issued and sold the Additional Shares to the underwriter. The Additional Shares were sold pursuant to the Company’s effective shelf registration statement on Form S-3ASR (File No. 333-229713) filed on February 15, 2019 and the related prospectus dated February 15, 2019, as supplemented by the prospectus supplement dated February 2, 2021 relating to the Additional Shares. A copy of the opinion of counsel of the Company relating to the validity of the Additional Shares is attached hereto as Exhibit 5.1.

In accordance with General Instruction B.2 of Form 8-K, the information contained in this Item 7.01 and Exhibit 99.1 is being furnished under Item 7.01 of Form 8-K and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall such information and exhibits be incorporated by reference into any filing under the Securities Act or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Item 9.01 Financial Statements and Exhibits.

(d)       Exhibits

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.