X0306 5 2017-06-05 0 0 1 0001679268 MAMMOTH ENERGY SERVICES, INC. TUSK 0000874499 GULFPORT ENERGY CORP 3001 QUAIL SPRINGS PARKWAY OKLAHOMA CITY OK 73134 1 0 1 0 Common Stock 2017-06-05 4 A 0 2098137 A 11181467 D On June 5, 2017, Gulfport Energy Corporation ("Gulfport") received 2,098,137 shares of common stock, par value $0.01 per share ("Common Stock"), of Mammoth Energy Services, Inc. (the "Issuer") from the Issuer as consideration for Gulfport's contribution of its membership interests in Sturgeon Acquisitions LLC, Stingray Energy Services LLC and Stingray Cementing LLC pursuant to three contribution agreements, each dated as of March 20, 2017, and as amended and restated on May 12, 2017, by and among Gulfport, the Issuer and certain other contributors party thereto, and each of which was approved in advance by the board of directors of the Issuer. Of these securities, 5,135 are unvested restricted stock units ("RSUs") that were granted under the Issuer's 2016 Equity Incentive Plan and were assigned to Gulfport by its director designees to the Issuer's board of directors under the terms of their respective employment with Gulfport. Such director designees previously reported the acquisition of the RSUs in their respective Form 4 filings and indicated that these were assigned to Gulfport. Of these 5,135 unvested RSUs, 2,222 will vest on October 19, 2018 and 2,913 will vest on the earlier of June 8, 2018 and the date of the Issuer's 2018 Annual Meeting of Stockholders. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer. /s/ Keri Crowell, Chief Financial Officer 2018-02-14