Definium Therapeutics, Inc. has a large shareholder group led by Commodore Capital LP reporting beneficial ownership of 7,428,775 common shares, representing 7.2% of the company as of December 31, 2025. This position includes 2,000,000 common shares plus 5,428,775 shares that can be acquired through a pre-funded warrant, which is subject to a 9.99% beneficial ownership limitation. The ownership percentage is based on 98,509,279 common shares reported outstanding as of October 31, 2025, plus the warrant shares. The filing is made jointly by Commodore Capital LP, Commodore Capital Master LP, and managing partners Robert Egen Atkinson and Michael Kramarz, who certify that the securities are not held for the purpose of changing or influencing control of the issuer. The issuer recently changed its name from Mind Medicine (MindMed) Inc. to Definium Therapeutics, Inc.
Positive
None.
Negative
None.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 2)
Definium Therapeutics, Inc.
(Name of Issuer)
Common Shares, no par value per share
(Title of Class of Securities)
24477V105
(CUSIP Number)
12/31/2025
(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 13G
CUSIP No.
24477V105
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
7,428,775.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
7,428,775.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
7,428,775.00
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)
7.2 %
12
Type of Reporting Person (See Instructions)
IA, PN
SCHEDULE 13G
CUSIP No.
24477V105
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
7,428,775.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
7,428,775.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
7,428,775.00
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)
7.2 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP No.
24477V105
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
7,428,775.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
7,428,775.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
7,428,775.00
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)
7.2 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
CUSIP No.
24477V105
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
7,428,775.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
7,428,775.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
7,428,775.00
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)
7.2 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
Definium Therapeutics, Inc.
(b)
Address of issuer's principal executive offices:
One World Trade Center, Suite 8500, New York, NEW YORK, 10007.
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:
Common Shares, no par value per share
(e)
CUSIP No.:
24477V105
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 December 31, 2025, the Firm may be deemed to beneficially own an aggregate of 7,428,775 shares Common Shares, no par value per share (the "Common Shares"), consisting of (i) 2,000,000 shares of the Common Shares and (ii) 5,428,775 shares of Common Shares each Filer has the right to acquire through the exercise of a pre-funded warrant ("Pre-Funded Warrant") of Definium Therapeutics, Inc. (the "Issuer"), which is subject to a beneficial ownership limitation of 9.99% (the "Beneficial Ownership Limitation"). 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 98,509,279 Common Stock reported as issued and outstanding as of October 31, 2025 in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 6, 2025, plus 5,428,775 shares of Common Shares which the Filers may acquire upon the exercise of the Pre-Funded Warrant, subject to the Beneficial Ownership Limitation.
The Issuer changed its name from Mind Medicine (MindMed) Inc. to Definium Therapeutics, Inc. effective January 9, 2026. Ownership information is reported as of December 31, 2025.
(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.
What percentage of Definium Therapeutics (DFTX) does Commodore Capital report owning?
Commodore Capital and related filers report beneficial ownership of 7.2% of Definium Therapeutics’ common shares. This is based on 7,428,775 shares deemed beneficially owned compared with 98,509,279 common shares reported outstanding, plus additional shares underlying a pre-funded warrant.
How many Definium Therapeutics (DFTX) shares does Commodore Capital beneficially own?
The group led by Commodore Capital reports beneficial ownership of 7,428,775 common shares. This consists of 2,000,000 common shares and 5,428,775 additional shares that each filer may acquire through exercising a pre-funded warrant in Definium Therapeutics.
What is the 9.99% beneficial ownership limitation mentioned for Definium Therapeutics (DFTX)?
The pre-funded warrant held by the filers has a 9.99% beneficial ownership limitation. This term restricts exercises of the warrant so that the holders’ beneficial ownership of Definium Therapeutics’ common shares does not exceed 9.99% at any time.
Who are the reporting persons in the Schedule 13G/A for Definium Therapeutics (DFTX)?
The reporting persons are Commodore Capital LP, Commodore Capital Master LP, Robert Egen Atkinson, and Michael Kramarz. Commodore Capital LP acts as investment manager to Commodore Capital Master LP, and Atkinson and Kramarz are managing partners exercising investment discretion.
As of what dates are Definium Therapeutics (DFTX) share counts measured in this filing?
Ownership is reported as of December 31, 2025, while the outstanding share count of 98,509,279 common shares comes from Definium Therapeutics’ Form 10-Q, which reported shares issued and outstanding as of October 31, 2025.
Did Definium Therapeutics (DFTX) recently change its corporate name?
Yes. The issuer is stated to have changed its name from Mind Medicine (MindMed) Inc. to Definium Therapeutics, Inc., effective January 9, 2026. The Schedule 13G/A reflects this updated corporate name alongside historical ownership data.
Are Commodore Capital’s Definium Therapeutics (DFTX) holdings intended to influence control of the company?
The filers certify that the securities were not acquired and are not held for the purpose of changing or influencing control of Definium Therapeutics. They also state the holdings are not part of any transaction having that purpose or effect, aside from certain nomination activities.
