Gran Tierra Energy holder reports 13.5% stake

Gran Tierra Energy Inc. is the subject of an amended Schedule 13D filing in which Equinox Partners Investment Management LLC, affiliated funds, and Sean M. Fieler report beneficial ownership of 4,781,471 shares of common stock.

Rhea-AI Filing Summary

Gran Tierra Energy Inc. is the subject of an amended Schedule 13D filing in which Equinox Partners Investment Management LLC, affiliated funds, and Sean M. Fieler report beneficial ownership of 4,781,471 shares of common stock. This represents approximately 13.5% of Gran Tierra’s outstanding common shares, based on 35,380,429 shares outstanding as disclosed in a recent quarterly report. The shares were acquired using clients’ investment capital, with an aggregate purchase cost of about $25,511,601.87, including commissions, and some positions may be held in margin accounts. The reporting group states it bought the stock because it viewed it as undervalued and may increase or decrease its holdings over time. It may also engage with management, the board, other shareholders, and potential acquirers, and may make proposals regarding capital allocation, capitalization, ownership structure (including a possible sale of the issuer), board composition, or operations. The filers disclaim beneficial ownership of shares they do not directly own, including 43,917 shares underlying deferred stock units awarded to former director Brad Virbitsky.

Filing Explained

This Amendment No. 3 states that the reporting group has no present plan or proposal for the listed corporate actions, although it may later buy or sell shares, communicate with stakeholders, or propose changes; those possibilities are not current commitments.

Key Figures

Shares beneficially owned (group total): 4,781,471 shares Ownership percentage: 13.5% Shares outstanding: 35,380,429 shares +5 more

8 metrics

Shares beneficially owned (group total) 4,781,471 shares Aggregate Gran Tierra Energy common shares reported as beneficially owned by the reporting persons

Ownership percentage 13.5% Portion of Gran Tierra’s outstanding common stock represented by 4,781,471 shares

Shares outstanding 35,380,429 shares Gran Tierra Energy common shares outstanding as cited from the Form 10-Q

Aggregate purchase amount $25,511,601.87 Total funds, including commissions, used by reporting persons’ clients to purchase the reported shares

Equinox Partners, L.P. holdings 1,936,337 shares Gran Tierra shares beneficially owned by Equinox Partners, L.P., about 5.5% of the class

Kuroto Fund holdings 494,508 shares Gran Tierra shares beneficially owned by Kuroto Fund, about 1.4% of the class

Mason Hill Partners holdings 412,332 shares Gran Tierra shares beneficially owned by Mason Hill Partners, about 1.2% of the class

Deferred stock units to former director 43,917 shares Gran Tierra deferred stock units awarded to Brad Virbitsky, convertible into common shares

Key Terms

beneficial ownership, Schedule 13D, margin accounts, deferred stock units, +2 more

6 terms

beneficial ownership regulatory

"The filing of this shall not be deemed an admission that the Reporting Persons are, for purposes of Section 13(d)... the beneficial owners"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

Schedule 13D regulatory

"The following constitutes Amendment No. 3 (this "Amendment No. 3") to the filed by the undersigned"

A Schedule 13D is a legal document that investors file with regulators when they buy a large enough stake in a company to potentially influence its management or decisions. It provides details about the investor’s intention, ownership stake, and plans, helping other investors understand who is gaining control and what their motives might be.

margin accounts financial

"The Reporting Persons may effect purchases of Shares through margin accounts maintained for EPIM's clients with prime brokers"

A margin account is a brokerage account that lets an investor borrow money from the broker to buy more securities than they could with cash alone, using the securities in the account as security for the loan. Think of it like a mortgage for stock purchases: borrowing increases potential gains but also magnifies losses, can trigger a forced sale if the account falls below required limits, and carries interest costs—factors investors must manage carefully.

deferred stock units financial

"Mr. Virbitsky was awarded deferred stock units by the Issuer that are convertible into 43,917 Shares"

Deferred stock units are promises from a company to give an employee shares of stock at a future date, often after certain conditions are met or after leaving the company. They function like a form of delayed compensation, allowing employees to earn shares over time. For investors, they represent potential future ownership in the company, but do not provide immediate voting rights or dividends until the shares are actually received.

capital allocation strategy financial

"making proposals to the Issuer concerning changes to the capital allocation strategy, capitalization, ownership structure"

A capital allocation strategy is a plan for deciding how a company distributes its financial resources among various needs, such as investing in growth, paying dividends, or reducing debt. For investors, it signals how effectively a company manages its money to create value and sustain long-term success, much like a person deciding how to divide their budget for savings, expenses, and investments.

dispositive power regulatory

"See rows (7) through (10)... for the sole or shared power to dispose or to direct the disposition"

Dispositive power is the authority to decide the final outcome of an asset, legal claim, contract, or corporate action — in effect the power to dispose of or resolve something. For investors it matters because whoever holds that authority can determine who gets paid, who controls an asset or vote, and how risks and returns are allocated; think of it like holding the key that lets you lock in the winner or loser in a deal.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What ownership stake in Gran Tierra Energy (GTE) is reported in this Schedule 13D/A?

The reporting group states it beneficially owns 4,781,471 Gran Tierra Energy shares, representing about 13.5% of the outstanding common stock, based on 35,380,429 shares outstanding in a recent quarterly report.

Who are the main reporting persons in Gran Tierra Energy (GTE)’s amended Schedule 13D?

The filing lists Equinox Partners Investment Management LLC, Equinox Partners, L.P., Kuroto Fund, Mason Hill Partners, and Sean M. Fieler as reporting persons, with shared voting and dispositive power over the reported Gran Tierra shares.

How much capital was used to purchase the Gran Tierra Energy (GTE) shares?

The reporting persons state that the Gran Tierra shares were bought with clients’ investment capital, with an aggregate purchase amount of approximately $25,511,601.87, including commissions, and that some positions may be held in margin accounts.

What percentage of Gran Tierra Energy (GTE) does Equinox Partners Investment Management LLC report?

Equinox Partners Investment Management LLC reports beneficial ownership of 4,781,471 shares, or about 13.5% of Gran Tierra’s outstanding common stock, through client accounts over which it has shared voting and dispositive power, while disclaiming beneficial ownership for Section 13 purposes.

What future actions do the reporting persons contemplate regarding Gran Tierra Energy (GTE)?

They indicate they may buy or sell more shares and may engage with management, the board, shareholders, and potential acquirers, including making proposals on capital allocation, capitalization, ownership structure (including a sale), board structure, or operations.

What board relationship is disclosed between Gran Tierra Energy (GTE) and Equinox Partners?

The filing notes that Brad Virbitsky, a portfolio manager and partner at Equinox Partners Investment Management LLC, served as an independent director of Gran Tierra from September 30, 2025 until his resignation on March 12, 2026, receiving 43,917 deferred stock units.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/07/2026 - 05:46 PM Accepted by SEC EDGAR 08/07/2026 - 05:46 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 3)

Gran Tierra Energy Inc.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

38500T200

(CUSIP Number)

Eric Wagner
Kleinberg, Kaplan, Wolff & Cohen P.C., 500 Fifth Avenue
New York, NY, 10110
(212) 880-9845

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

08/05/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 38500T200

1

Name of reporting person

Equinox Partners Investment Management LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 4,781,471.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4,781,471.00

11

Aggregate amount beneficially owned by each reporting person

4,781,471.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

13.5 %

14

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person:

Note to Row 8: Includes 1,938,294 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).

SCHEDULE 13D

CUSIP Number(s): 38500T200

1

Name of reporting person

Equinox Partners, L.P.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 1,936,337.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,936,337.00

11

Aggregate amount beneficially owned by each reporting person

1,936,337.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

5.5 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s): 38500T200

1

Name of reporting person

Kuroto Fund LP

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 494,508.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 494,508.00

11

Aggregate amount beneficially owned by each reporting person

494,508.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

1.4 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s): 38500T200

1

Name of reporting person

Mason Hill Partners, LP

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 412,332.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 412,332.00

11

Aggregate amount beneficially owned by each reporting person

412,332.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

1.2 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s): 38500T200

1

Name of reporting person

Sean M. Fieler

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 4,781,471.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4,781,471.00

11

Aggregate amount beneficially owned by each reporting person

4,781,471.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

13.5 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

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).

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.001 per share
(b)	Name of Issuer: Gran Tierra Energy Inc.
(c)	Address of Issuer's Principal Executive Offices: 500 Centre Street S.E., Calgary, ALBERTA, CANADA , T2G 1A6.
Item 1 Comment: The following constitutes Amendment No. 3 (this "Amendment No. 3") 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. 3 amends the Schedule 13D as specifically set forth herein.
Item 3.	Source and Amount of Funds or Other Consideration
	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 $25,511,601.87, 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 4.	Purpose of Transaction
	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. Mr. Virbitsky resigned from the Issuer's Board of Directors on March 12, 2026. 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.
Item 5.	Interest in Securities of the Issuer
(a)	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 35,380,429 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 August 5, 2026. As of the date hereof, the Reporting Persons beneficially own an aggregate of 4,781,471 Shares, constituting approximately 13.5% 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. Brad Virbitsky, an EPIM employee, was appointed to the Issuer's Board of Directors as an independent director effective September 30, 2025, and resigned from the Issuer's Board of Directors on March 12, 2026. Mr. Virbitsky was awarded deferred stock units by the Issuer that are convertible into 43,917 Shares as compensation for his serving as a member of the Issuer's Board of Directors. The Reporting Persons disclaim beneficial ownership of any Shares held by Mr. Virbitsky.
(c)	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.
(d)	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.
(e)	Not applicable.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Equinox Partners Investment Management LLC

Signature:	/s/ Sean M. Fieler
Name/Title:	Manager
Date:	08/07/2026

Equinox Partners, L.P.

Signature:	/s/ Sean M. Fieler
Name/Title:	Manager of Equinox Partners Investment Management LLC, the Investment Manager of Equinox Partners, L.P.
Date:	08/07/2026

Kuroto Fund LP

Signature:	/s/ Sean M. Fieler
Name/Title:	Manager of Equinox Partners Investment Management LLC, the Investment Manager of Kuroto Fund LP
Date:	08/07/2026

Mason Hill Partners, LP

Signature:	/s/ Sean M. Fieler
Name/Title:	Manager of Equinox Partners Investment Management LLC, the Investment Manager of Mason Hill Partners, LP
Date:	08/07/2026

Sean M. Fieler

Signature:	/s/ Sean M. Fieler
Name/Title:	SEAN M. FIELER
Date:	08/07/2026