SCHEDULE 13D/A 0000938552 XXXXXXXX LIVE 2 Common Stock, par value $0.001 per share 11/17/2025 true 0001273441 38500T200 Gran Tierra Energy Inc.

500 Centre Street S.E. Calgary A0 T2G 1A6

Eric Wagner (212) 880-9845 Kleinberg, Kaplan, Wolff & Cohen P.C. 500 Fifth Avenue New York NY 10110 0000938552 N Equinox Partners Investment Management LLC a OO DE 0 6219896 0 6219896 6219896 17.6 IA Note to Row 8: Includes 2,465,673 shares of Common Stock, par value $0.001 per share (the "Shares") of Gran Tierra Energy Inc. (the "Issuer") held in one or more client accounts over which Equinox Partners Investment Management LLC, as investment advisor, has shared voting and dispositive power. The filing of this statement should not be deemed as admission that Equinox Partners Investment Management LLC is, for the purposes of Section 13 of the Act, the beneficial owner of the Shares held in such client account(s). 0000933897 N Equinox Partners, L.P. a WC DE 0 2543910 0 2543910 2543910 7.2 PN 0001080716 N Kuroto Fund LP a WC DE 0 659996 0 659996 659996 1.9 PN 0001421771 N Mason Hill Partners, LP a WC DE 0 550317 0 550317 550317 1.6 PN Y Sean M. Fieler a OO X1 0 6219896 0 6219896 6219896 17.6 IN Note to Row 8: See Footnote 1 on page 2. The filing of this statement should not be deemed an admission that Mr. Fieler is, for the purposes of Section 13 of the Act, the beneficial owner of the Shares held in such client account(s). Common Stock, par value $0.001 per share Gran Tierra Energy Inc. 500 Centre Street S.E. Calgary A0 T2G 1A6 The following constitutes Amendment No. 2 (this "Amendment No. 2") to the Schedule 13D (as previously amended, the "Schedule 13D") filed by the undersigned with respect to shares of the Common Stock, par value $0.001 per share (the "Shares") of Gran Tierra Energy Inc. (the "Issuer"). This Amendment No. 2 amends the Schedule 13D as specifically set forth herein. Item 3 of the Schedule 13D is hereby amended and restated in its entirety as follows: All of the Shares to which this Schedule 13D relates were purchased using the investment capital of the applicable clients of EPIM. The aggregate amount of funds used for the purchase of the Shares held by the Reporting Persons is approximately $39,183,972.34, including commissions. The Reporting Persons may effect purchases of Shares through margin accounts maintained for EPIM's clients with prime brokers, which extend margin credit as and when required to open or carry positions in their margin accounts, subject to applicable federal margin regulations, stock exchange rules and such firms' credit policies. Shares may be held in margin accounts and may be pledged as collateral security for the repayment of debit balances in such accounts. Since other securities may be held in such margin accounts, it may not be possible to determine the amounts, if any, of margin used to purchase the Shares. Item 5 of the Schedule 13D is hereby amended and restated in its entirety as follows: (a) - (b) The aggregate percentage of Shares reported owned by the Reporting Persons is based upon 35,295,753 Shares outstanding, which is the total number of Shares outstanding as reported in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on October 31, 2025. As of the date hereof, the Reporting Persons beneficially own an aggregate of 6,219,896 Shares, constituting approximately 17.6% of the outstanding Shares. See rows (11) and (13) of the cover pages to this Schedule 13D for the aggregate number of Shares and percentage of the outstanding Shares beneficially owned by each of the Reporting Persons. See rows (7) through (10) of the cover pages to this Schedule 13D, including the notes relating thereto, for the number of Shares as to which each Reporting Person has the sole or shared power to vote or direct the vote and the sole or shared power to dispose or to direct the disposition. The filing of this Schedule 13D shall not be deemed an admission that the Reporting Persons are, for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, the beneficial owners of any securities of the Issuer that he or it does not directly own. Each of the Reporting Persons specifically disclaims beneficial ownership of the securities reported herein that he or it does not directly own. The Reporting Persons expect that Brad Virbitsky, a portfolio manager and partner at EPIM who was appointed to the Issuer's Board of Directors as an independent director effective September 30, 2025, will be awarded certain securities of the Issuer as compensation for his serving as a member of the Issuer's Board of Directors. See Item 5(a). During the past sixty (60) days, the Reporting Persons have not entered into any transactions in the Shares except as set forth on Schedule 1 hereto or as previously reported on Schedule 13D. No Person is known to the Reporting Persons to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, any Shares that may be beneficially owned by the Reporting Persons. Not applicable. Exhibit 99 - Schedule 1 Equinox Partners Investment Management LLC /s/ Sean M. Fieler 11/19/2025 Equinox Partners, L.P. /s/ Sean M. Fieler 11/19/2025 Kuroto Fund LP /s/ Sean M. Fieler 11/19/2025 Mason Hill Partners, LP /s/ Sean M. Fieler 11/19/2025 Sean M. Fieler /s/ Sean M. Fieler 11/19/2025