13G Filing: Carlson Capital and Propetro Holding Corp.

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Item 1(a). NAME OF ISSUER

ProPetro Holding Corp. (the Issuer).

Item 1(b). ADDRESS OF ISSUERS PRINCIPAL EXECUTIVE OFFICES

1706 S. Midkiff, Bldg. B

Midland, Texas 79701

Item 2(a). NAME OF
PERSON FILING

This statement is filed by:

(i) Double Black Diamond Offshore Ltd., a Cayman Islands exempted company (Double Offshore), with respect to the Common Stock (as
defined below) directly held by it;

(ii) Black Diamond Offshore Ltd., a Cayman Islands exempted company (Offshore), with
respect to the Common Stock directly held by it;

(iii) Black Diamond Energy L/S Offshore Ltd., a Cayman Islands exempted company
(Energy and together with Double Offshore and Offshore, the Funds), with respect to the Common Stock directly held by it;

(iv) Carlson Capital L.P., a Delaware limited partnership (Carlson Capital), which serves as the investment manager to the Funds,
with respect to the Common Stock directly held by the Funds;

(v) Asgard Investment Corp. II, a Delaware corporation (Asgard
II), which serves as the general partner of Carlson Capital, with respect to the Common Stock directly held by the Funds;

(vi)
Asgard Investment Corp., a Delaware corporation (Asgard), which is the sole stockholder of Asgard II, with respect to the Common Stock directly held by the Funds; and

(vii) Mr. Clint D. Carlson, a United States citizen (Mr. Carlson), who serves as president of Asgard, Asgard II and
Carlson Capital, with respect to the Common Stock directly held by the Funds.

The foregoing persons are hereinafter sometimes collectively
referred to as the Reporting Persons.

The filing of this statement should not be construed as an admission that any of the
Reporting Persons is, for the purposes of Section 13 of the Act, the beneficial owner of the Common Stock reported herein.

Item 2(b).
ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE

The address of the principal business office of each of the Reporting
Persons is 2100 McKinney Avenue, Suite 1800, Dallas, Texas 75201.

Item 2(c). CITIZENSHIP

Each of the Funds is a Cayman Islands exempted company. Carlson Capital is a Delaware limited partnership. Each of Asgard and Asgard II is a
Delaware corporation. Mr. Carlson is a United States citizen.

Item 2(d). TITLE OF CLASS OF SECURITIES

Common Stock, par value $0.01 per share (the Common Stock).

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