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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

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SCHEDULE 13D/A

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 3)*

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Liberty Oilfield Services Inc.

(Name of Issuer)

Class A Common Stock, $0.01 par value per share

(Title of Class of Securities)

53115L 104

(CUSIP Number)

Dianna Rosser Aprile

c/o Riverstone Holdings, LLC

712 Fifth Avenue, 36th Floor

New York, New York 10019

(212) 993-0076

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

(with a copy to)

Jeffrey S. Hochman

Willkie Farr & Gallagher LLP

787 Seventh Avenue

New York, New York 10019

(212) 728-8000

July 23, 2019

(Date of Event Which Requires Filing of Statement on Schedule 13D)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), checking the following box. ☐

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

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Explanatory Note

This Amendment No. 3 to Schedule 13D (this “Amendment No. 3”) amends and supplements the Schedule 13D filed with the Securities and Exchange Commission on January 26, 2018, as amended by Amendment No. 1 to Schedule 13D/A, filed on September 14, 2018, as amended by Amendment No. 2 to Schedule 13D/A, filed on July 11, 2019 (the “Current Schedule 13D”), relating to the Class A common stock, par value $0.01 per share (the “Common A Shares”), of Liberty Oilfield Services Inc. (the “Issuer”). The Common A Shares and Class B common stock, par value $0.01 per share, of the Issuer (the “Common B Shares” and, together with the Common A Shares, the “Common Shares”) are treated as a single class for purposes of this Schedule 13D because they vote together as a single class. Capitalized terms used herein without definition shall have the meaning set forth in the Current Schedule 13D.

Item 6 of the Current Schedule 13D is hereby amended and supplemented as follows:

On July 23, 2019, the Issuer,  R/C Energy IV Direct Partnership, L.P. and R/C IV Liberty Holdings, L.P. (together, “Riverstone”) entered into an additional Stockholders Agreement (the “Additional Agreement”). Pursuant to the Additional Agreement, the Issuer agreed to use reasonable best efforts to cause the board of directors of the Issuer (the “Board”) to, in the case where Riverstone and its affiliates beneficially own (as such term is defined under Rule 13(d)-3 promulgated under the Securities Exchange Act of 1934, as amended) at least 10% of the outstanding Common A Shares, and the Board is comprised of five or more directors that are not Riverstone nominees, elect one additional nominee designated by Riverstone to serve on the Board. Four directors appointed by Riverstone currently serve on the Board pursuant to the terms of that certain Stockholders Agreement, dated January 17, 2018, by and among the Issuer, Riverstone and the other parties thereto (the “Original Agreement”). The Additional Agreement does not limit or replace the rights of Riverstone under the Original Agreement.