JATT III Acquisition gets new 5.2% fund holder

Rhea-AI Filing Summary

JATT III Acquisition Corp (JTTT) has a new significant shareholder group, as Commodore Capital LP, Commodore Capital Master LP, and managing partners Robert Egen Atkinson and Michael Kramarz report beneficial ownership of 400,000 ordinary shares of the company. Based on 7,725,000 ordinary shares outstanding as of August 25, 2026, this represents 5.2% of the class. The filing states that the filers have shared voting and dispositive power over all 400,000 shares and no sole voting or dispositive power. Commodore Capital LP is identified as investment manager to Commodore Capital Master LP, with Atkinson and Kramarz exercising investment discretion.

Key Figures

Shares beneficially owned: 400,000 ordinary shares Percentage of class: 5.2% Shares outstanding: 7,725,000 ordinary shares +4 more

7 metrics

Shares beneficially owned 400,000 ordinary shares Beneficial ownership in JATT III Acquisition Corp as of August 26, 2026

Percentage of class 5.2% Ownership percentage of JATT III Acquisition Corp ordinary shares

Shares outstanding 7,725,000 ordinary shares JATT III Acquisition Corp shares issued and outstanding as of August 25, 2026

Sole voting power 0 shares Sole power to vote or direct the vote for each filer

Shared voting power 400,000 shares Shared power to vote or direct the vote for each filer

Sole dispositive power 0 shares Sole power to dispose or direct disposition for each filer

Shared dispositive power 400,000 shares Shared power to dispose or direct disposition for each filer

Key Terms

beneficially own, investment manager, Rule 424(b)(4) Prospectus Supplement, Joint Filing Agreement

4 terms

beneficially own financial

"the Firm may be deemed to beneficially own an aggregate of 400,000 ordinary shares"

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

investment manager financial

"The Firm is the investment manager to Commodore Master"

Rule 424(b)(4) Prospectus Supplement regulatory

"reported as issued and outstanding on August 25, 2026, in the Issuer's Rule 424(b)(4) Prospectus Supplement"

Joint Filing Agreement regulatory

"Exhibit 1: Joint Filing Agreement"

FAQ

What stake in JATT III Acquisition Corp (JTTT) is reported in this Schedule 13G?

The filing reports that the filers beneficially own 400,000 ordinary shares of JATT III Acquisition Corp, representing 5.2% of the outstanding class based on 7,725,000 ordinary shares outstanding as of August 25, 2026.

Who are the reporting persons in this JTTT Schedule 13G?

The reporting persons are Commodore Capital LP, Commodore Capital Master LP, Robert Egen Atkinson, and Michael Kramarz, each referred to as a “Filer.” Commodore Capital LP is the investment manager to Commodore Capital Master LP.

What voting and dispositive power do the filers report over JTTT shares?

Each filer reports 0 shares with sole voting or dispositive power and 400,000 shares with shared voting and shared dispositive power over JATT III Acquisition Corp ordinary shares.

How was the 5.2% ownership of JTTT calculated?

The 5.2% ownership figure is based on 7,725,000 ordinary shares of JATT III Acquisition Corp reported as issued and outstanding as of August 25, 2026 in a Rule 424(b)(4) Prospectus Supplement.

What roles do Robert Egen Atkinson and Michael Kramarz play in relation to JTTT shares?

Robert Egen Atkinson and Michael Kramarz are managing partners of Commodore Capital LP and exercise investment discretion with respect to the 400,000 ordinary shares of JATT III Acquisition Corp reported as beneficially owned.

What is the relationship between Commodore Capital LP and Commodore Capital Master LP regarding JTTT?

The filing states that Commodore Capital LP is the investment manager to Commodore Capital Master LP and, in that capacity, may be deemed to beneficially own the 400,000 ordinary shares of JATT III Acquisition Corp held for Commodore Capital Master LP.

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Available on EDGAR 09/02/2026 - 04:21 PM Accepted by SEC EDGAR 09/02/2026 - 04:21 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

JATT III Acquisition Corp

(Name of Issuer)

ordinary shares, par value $0.0001 per share

(Title of Class of Securities)

G5080G109

(CUSIP Number)

08/26/2026

(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)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): G5080G109

1

Names of Reporting Persons

Commodore Capital LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 400,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 400,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

400,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.2 %

12

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13G

CUSIP Number(s): G5080G109

1

Names of Reporting Persons

Commodore Capital Master LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 400,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 400,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

400,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.2 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): G5080G109

1

Names of Reporting Persons

Robert Egen Atkinson

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 400,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 400,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

400,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.2 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

CUSIP Number(s): G5080G109

1

Names of Reporting Persons

Michael Kramarz

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 400,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 400,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

400,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.2 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: JATT III Acquisition Corp
(b)	Address of issuer's principal executive offices: 153 Central Avenue C/O 56, Westfield, NEW JERSEY, 07091.
Item 2.
(a)	Name of person filing: Commodore Capital LP Commodore Capital Master LP Robert Egen Atkinson Michael Kramarz Each a "Filer."
(b)	Address or principal business office or, if none, residence: The address for Commodore Capital LP, Robert Egen Atkinson, and Michael Kramarz is 444 Madison Avenue, Floor 35, New York, NY 10022. The address for Commodore Capital Master LP is c/o Maples Corporate Services Limited, Ugland House, South Church Street, PO Box 309, Grand Cayman KY1-1104, Cayman Islands.
(c)	Citizenship: See Item 4 of the cover page for each Filer.
(d)	Title of class of securities: ordinary shares, par value $0.0001 per share
(e)	CUSIP Number(s): G5080G109
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: See Item 9 of the cover page for each Filer. This report on Schedule 13G is being filed by Commodore Capital LP (the "Firm"), Commodore Capital Master LP ("Commodore Master"), Michael Kramarz, and Robert Egen Atkinson. The Firm is the investment manager to Commodore Master. As of August 26, 2026, the Firm may be deemed to beneficially own an aggregate of 400,000 ordinary shares, par value $0.0001 per share (the "Ordinary Shares") of JATT III Acquisition Corp. (the "Issuer"). The Firm, as the investment manager to Commodore Master, may be deemed to beneficially own these securities. Michael Kramarz and Robert Egen Atkinson are the managing partners of the Firm and exercise investment discretion with respect to these securities. Ownership percentages are based on 7,725,000 shares of Ordinary Shares reported as issued and outstanding on August 25, 2026, in the Issuer's Rule 424(b)(4) Prospectus Supplement filed with the Securities and Exchange Commission on August 26, 2026.
(b)	Percent of class: See Item 11 of the cover page for each Filer.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See Item 5 of the cover page for each Filer.
	(ii) Shared power to vote or to direct the vote: See Item 6 of the cover page for each Filer.
	(iii) Sole power to dispose or to direct the disposition of: See Item 7 of the cover page for each Filer.
	(iv) Shared power to dispose or to direct the disposition of: See Item 8 of the cover page for each Filer.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

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.

Commodore Capital LP

Signature:	Michael Kramarz
Name/Title:	Managing Partner
Date:	09/02/2026

Commodore Capital Master LP

Signature:	Michael Kramarz
Name/Title:	Authorized Signatory
Date:	09/02/2026

Robert Egen Atkinson

Signature:	Robert Egen Atkinson
Name/Title:	Authorized Signatory
Date:	09/02/2026

Michael Kramarz

Signature:	Michael Kramarz
Name/Title:	Authorized Signatory
Date:	09/02/2026

Exhibit Information

Exhibit 1: Joint Filing Agreement