Please wait

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13D/A 0001387131-23-000258 0001360554 XXXXXXXX LIVE 4 Common Stock, par value $0.01 per share 01/05/2026 false 0001084991 63886Q109 NATURAL GAS SERVICES GROUP INC 404 VETERANS AIRPARK LANE SUITE 300 Midland TX 79705 Hoak Public Equities, L.P. (214) 855-2284 3963 Maple Avenue, Suite 450 Dallas TX 75219 0001360554 N Hoak Public Equities, LP a WC N TX 838128.00 0.00 838128.00 0.00 838128.00 N 6.67 PN The item (13) calculation is based on 12,568,917 shares of Common Stock of the Issuer outstanding as of November 7, 2025, as disclosed on the Issuer's Form 10-Q filed with the SEC on November 10, 2025. 0001607736 N Hoak Fund Management, L.P. a AF N TX 838128.00 0.00 838128.00 0.00 838128.00 N 6.67 PN The item (13) calculation is based on 12,568,917 shares of Common Stock of the Issuer outstanding as of November 7, 2025, as disclosed on the Issuer's Form 10-Q filed with the SEC on November 10, 2025. 0001607735 N Hoak & Co. a AF N TX 838128.00 0.00 838128.00 0.00 838128.00 N 6.67 CO The item (13) calculation is based on 12,568,917 shares of Common Stock of the Issuer outstanding as of November 7, 2025, as disclosed on the Issuer's Form 10-Q filed with the SEC on November 10, 2025. 0001450326 N Hoak J. Hale a AF N X1 838128.00 0.00 838128.00 0.00 838128.00 N 6.67 IN The item (13) calculation is based on 12,568,917 shares of Common Stock of the Issuer outstanding as of November 7, 2025, as disclosed on the Issuer's Form 10-Q filed with the SEC on November 10, 2025. 0001607722 N HOAK JAMES M a AF N X1 838128.00 0.00 838128.00 0.00 838128.00 N 6.67 IN The item (13) calculation is based on 12,568,917 shares of Common Stock of the Issuer outstanding as of November 7, 2025, as disclosed on the Issuer's Form 10-Q filed with the SEC on November 10, 2025. Common Stock, par value $0.01 per share NATURAL GAS SERVICES GROUP INC 404 VETERANS AIRPARK LANE SUITE 300 Midland TX 79705 This Amendment No. 4 to Schedule 13D ("Amendment No. 4") amends and supplements the Schedule 13D originally filed with the Securities and Exchange Commission ("SEC") on November 28, 2022 (the "Original 13D") and Amendment No. 1 to the statement on Schedule 13D filed with the Securities and Exchange Commission on December 9, 2022 ("Amendment No. 1") and Amendment No. 2 to the statement on Schedule 13D filed with the Securities and Exchange Commission on December 30, 2022 ("Amendment No. 2") and Amendment No. 3 to the statement on Schedule 13D filed with the Securities and Exchange Commission on January 11, 2023 ("Amendment No. 3" and together with the Original 13D, Amendment No. 1, Amendment No. 2, Amendment No. 3 and this Amendment No. 4., the "Schedule 13D"). Unless otherwise indicated, all capitalized terms used but not defined herein shall have the same meaning ascribed to them in the Original 13D. This Amendment No. 4 is being filed to make amendments to the Schedule 13D as follows: Item 3 is hereby amended and restated to read in its entirety as follows: "The total amount of funds used for the purchase of Common Stock by HPE was $13,427,930.38. All of the shares of Common Stock beneficially owned by HPE were paid for using working capital of HPE. Hoak Management does not directly hold any Common Stock but may be deemed to beneficially own the Common Stock owned by HPE. The other Reporting Persons do not hold shares of Common Stock directly but may be deemed to beneficially own the Common Stock owned by HPE." Item 5(a) is hereby amended and restated to read in its entirety as follows: (a) As of the date of this Schedule 13D, based upon 12,568,917 shares of Common Stock outstanding (as disclosed on the Issuer's Form 10-Q filed with the SEC November 10, 2025): (a) HPE directly owns an aggregate of 838,128 shares of Common Stock, representing approximately 6.67% of the outstanding Common Stock; (b) Hoak Management, in its capacity as HPE's general partner, may be deemed to beneficially own an aggregate of 838,128 shares of Common Stock, representing approximately 6.67% of the outstanding Common Stock; and (c) each of Hoak and Co. (in its capacity as the general partner of Hoak Management), James M. Hoak (in his capacity as Hoak & Co.'s controlling shareholder), and J. Hale Hoak (in his capacity as Hoak & Co.'s President) may be deemed to beneficially own an aggregate of 838,128 shares of Common Stock, representing approximately 6.67% of the outstanding Common Stock." Item 5(c) is hereby amended and restated to read in its entirety as follows: Schedule A hereto sets forth all transactions in the Common Stock within the past 60 days by any Reporting Person. All such transactions were effected on the open market. Except for the transactions set forth on Schedule A, none of the Reporting Persons effected any transaction in the Common Stock during the past 60 days. 99.1 Joint Filing Agreement dated January 7, 2026, by and among Hoak Public Equities, L.P., Hoak Fund Management, L.P., Hoak & Co., James M. Hoak and J. Hale Hoak. 99.2 Schedule A - all transactions in the Common Stock within the past 60 days by any Reporting Person. Hoak Public Equities, LP /s/ J. Hale Hoak J. Hale Hoak, President (Hoak & Co., its general partner) 01/07/2026 Hoak Fund Management, L.P. /s/ J. Hale Hoak J. Hale Hoak, President (Hoak & Co., its general partner) 01/07/2026 Hoak & Co. /s/ J. Hale Hoak J. Hale Hoak, President 01/07/2026 Hoak J. Hale /s/ J. Hale Hoak J. Hale Hoak 01/07/2026 HOAK JAMES M /s/ James M. Hoak James M. Hoak 01/07/2026