SEC Form SCHEDULE 13D filed by Gran Tierra Energy Inc.

The principal business address for each of the Reporting Persons is Three Stamford Plaza, 301 Tresser Blvd, 13th Fl., Stamford, CT 06901.

EPIM's principal business is serving as an investment advisor to certain private investment funds, including Equinox Partners, Kuroto, Mason Hill Partners, and other client accounts. Each of Equinox Partners, Kuroto, and Mason Hill Partners is a private investment fund. Mr. Fieler owns a controlling interest in, and is the managing member of, EPIM

During the last five years, none of the Reporting Persons have: (i) been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors); or (ii) been party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

During the last five years, none of the Reporting Persons have: (i) been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors); or (ii) been party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

EPIM is a Delaware limited liability company. Equinox Partners is a Delaware limited partnership. Kuroto is a Delaware limited partnership. Mason Hill Partners is a Delaware limited partnership. Mr. Fieler is a citizen of the United States.

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 $34,577,851, 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.

The Reporting Persons purchased the Shares based on the Reporting Persons' belief that the Shares, when purchased, were undervalued and represented an attractive investment opportunity. Depending upon overall market conditions, other investment opportunities available to the Reporting Persons, and the availability of Shares at prices that would make the purchase or sale of Shares desirable, the Reporting Persons may endeavor to increase or decrease their position in the Issuer through, among other things, the purchase or sale of Shares on the open market or in private transactions or otherwise, on such terms and at such times as the Reporting Persons may deem advisable. Brad Virbitsky, a portfolio manager and partner at EPIM, was appointed to the Issuer's Board of Directors as an independent director, effective September 30, 2025, prompting the change from a 13G to a 13D filer. No Reporting Person has any present plan or proposal which would relate to or result in any of the matters set forth in Item 4(a) through (j) of this Schedule 13D except as set forth herein or such as would occur upon or in connection with completion of, or following, any of the actions discussed herein. The Reporting Persons intend to review their investment in the Issuer on a continuing basis. Depending on various factors including, without limitation, the Issuer's financial position and investment strategy, the price levels of the Shares, conditions in the securities markets and general economic and industry conditions, the Reporting Persons may in the future take such actions with respect to their investment in the Issuer as they deem appropriate including, without limitation, engaging in communications with management and the Board of Directors, engaging in discussions with stockholders of the Issuer or third parties, including potential acquirers and service providers, about the Issuer and the Reporting Persons' investment, making proposals to the Issuer concerning changes to the capital allocation strategy, capitalization, ownership structure, including a sale of the Issuer as a whole or in parts, Board of Directors structure (including Board of Directors composition) or operations of the Issuer, purchasing additional Shares, selling some or all of their Shares, engaging in short selling of or any hedging or similar transaction with respect to the Shares, or changing their intention with respect to any and all matters referred to in Item 4.

The aggregate percentage of Shares reported owned by the Reporting Persons is based upon 35,290,955 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 July 31, 2025. As of the date hereof, the Reporting Persons beneficially own an aggregate of 5,097,688 Shares, constituting approximately 14.4% 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 Mr. Virbitsky 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) above.

The Reporting Persons have not entered into any transactions in Shares during the past sixty days.

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.

Except as described above, the only agreement that the Reporting Persons have entered into is a joint filing agreement, dated as October 6, 2025, a copy of which is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

Exhibit 99.1 Joint Filing Agreement to Schedule 13D by and among Equinox Partners Investment Management LLC, Equinox Partners, L.P., Kuroto Fund LP, Mason Hill Partners, LP and Sean M. Fieler dated as of October 6, 2025.