SCHEDULE 13G/A: Statement of Beneficial Ownership by Certain Investors
Published on August 14, 2026
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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549 | |
SCHEDULE 13G | |
UNDER THE SECURITIES EXCHANGE ACT OF 1934
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(Amendment No. 1)
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Definium Therapeutics, Inc. (Name of Issuer) | |
Common Stock (Title of Class of Securities) | |
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06/30/2026 (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)
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 Rule 13d-1(c)
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| Rule 13d-1(d)
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SCHEDULE 13G
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| CUSIP Number(s): | 24477V105 |
| 1 | Names of Reporting Persons
DRIEHAUS CAPITAL MANAGEMENT LLC | ||||||||
| 2 | Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
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| 3 | Sec Use Only | ||||||||
| 4 | Citizenship or Place of Organization
DELAWARE
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 9 | Aggregate Amount Beneficially Owned by Each Reporting Person
6,845,276.00 | ||||||||
| 10 | Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
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| 11 | Percent of class represented by amount in row (9)
5.36 % | ||||||||
| 12 | Type of Reporting Person (See Instructions)
IA |
Comment for Type of Reporting Person: The issuer changed its name from Mind Medicine (MindMed), Inc. to Definium Therapeutics, Inc. on January 12, 2026. This amendment is filed to reflect the change in our percentage of ownership of Definium Therapeutics, Inc. (DFTX). DCM owned 5.36% of DFTX as of June 30, 2026, down from 6.64% as of December 31, 2025.
SCHEDULE 13G
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| 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:
Driehaus Capital Management LLC | |
| (b) | Address or principal business office or, if none, residence:
25 East Erie Street, Chicago, Illinois 60611 | |
| (c) | Citizenship:
USA | |
| (d) | Title of class of securities:
Common Stock | |
| (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);
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| (b) | Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
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| (c) | Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
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| (d) | Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
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| (e) | An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
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| (f) | An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
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| (g) | A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
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| (h) | A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
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| (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);
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| (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).
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| Item 4. | Ownership | |
| (a) | Amount beneficially owned:
6845276 | |
| (b) | Percent of class:
5.36 %
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| (c) | Number of shares as to which the person has:
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| (i) Sole power to vote or to direct the vote:
0 | ||
| (ii) Shared power to vote or to direct the vote:
6845276 | ||
| (iii) Sole power to dispose or to direct the disposition of:
0 | ||
| (iv) Shared power to dispose or to direct the disposition of:
6845276 | ||
| Item 5. | Ownership of 5 Percent or Less of a Class. | |
Not Applicable
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| Item 6. | Ownership of more than 5 Percent on Behalf of Another Person. | |
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.
The shares reported by Driehaus Capital Management LLC (DCM) are held by numerous clients on a fully discretionary basis in accounts managed by DCM. Securities held in these clients' accounts are included in this report to reflect that DCM may have voting power and has dispositive power. To the best of DCM's knowledge, none of the referenced clients have the right to receive dividends or direct proceeds from the sale of interests relating to more than 5% of the class. | ||
| 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
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| Item 8. | Identification and Classification of Members of the Group. | |
Not Applicable
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| Item 9. | Notice of Dissolution of Group. | |
Not Applicable
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| Item 10. | Certifications: |
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and 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.
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