Definium CMO granted 200K shares in award

Definium Therapeutics’ Chief Medical Officer received a 200,000-share performance-based equity grant, raising his direct holdings to 803,699 common shares.

Rhea-AI Filing Summary

Definium Therapeutics, Inc. (DFTX) reported that its Chief Medical Officer, Daniel Karlin, acquired 200,000 common shares on September 14, 2026 through a grant categorized as a grant or award, at a reported price of $0.00 per share. These shares represent the third tranche of performance share units granted effective March 12, 2025, which remain subject to vesting based on Dr. Karlin’s continued employment through March 12, 2028 and the achievement of specified clinical and regulatory milestones. Following this grant and including 417 shares acquired under the 2024 Employee Share Purchase Plan on August 17, 2026, Dr. Karlin directly holds 803,699 common shares. No Rule 10b5-1 trading plan is reported for this transaction.

Insider Trade Summary

Grant/Award: 200,000 shares

Grant/Award 1 txn

Insider Karlin Daniel

Role Chief Medical Officer

Type	Security	Shares	Price	Value
Grant/Award	Common Shares F1, F2	200,000	$0.00	$0.00

Holdings After Transaction: Common Shares — 803,699 shares (Direct)

Footnotes (2)

1. F1. The common shares represent the third tranche of performance share units granted effective March 12, 2025, and remain subject to vesting based on the Reporting Person's continued employment through March 12, 2028. Each performance share unit represented a contingent right to receive one common share based on, and subject to, the achievement of certain clinical and regulatory milestones set forth in the Performance Share Unit Award Agreement.
2. F2. Amount includes 417 shares acquired under the Definium Therapeutics, Inc. 2024 Employee Share Purchase Plan on August 17, 2026.

Key Figures

Common shares granted: 200,000 shares Reported grant price per share: $0.00 per share Total common shares held after transaction: 803,699 shares +3 more

6 metrics

Common shares granted 200,000 shares Grant or award acquisition reported for September 14, 2026

Reported grant price per share $0.00 per share Price field for the 200,000-share grant transaction

Total common shares held after transaction 803,699 shares Direct holdings of Daniel Karlin following the reported grant

Shares acquired under 2024 Employee Share Purchase Plan 417 shares Additional shares included in total holdings, acquired August 17, 2026

Performance share unit grant effective date March 12, 2025 Original grant date of the performance share units underlying this third tranche

Vesting employment date March 12, 2028 Continued employment required through this date for vesting of the performance share units

Key Terms

performance share units, Employee Share Purchase Plan, clinical and regulatory milestones, contingent right

4 terms

performance share units financial

"The common shares represent the third tranche of performance share units granted"

Performance share units are a type of company stock award given to employees that depend on the company meeting specific goals or targets. If these goals are achieved, the employee receives shares or the value of shares; if not, they may receive little or no compensation. This aligns employees’ interests with the company's success and encourages performance that benefits investors.

Employee Share Purchase Plan financial

"shares acquired under the Definium Therapeutics, Inc. 2024 Employee Share Purchase Plan"

A program that lets employees buy their employer’s stock, often through regular payroll deductions and sometimes at a discounted price or with matching contributions; think of it as a company-run savings plan that converts part of pay into ownership. It matters to investors because it can increase insider ownership and employee motivation, potentially affecting company performance, and can slightly change share supply when new stock is issued or sold.

clinical and regulatory milestones medical

"subject to, the achievement of certain clinical and regulatory milestones"

Clinical and regulatory milestones are the key steps a medical product must clear as it is tested on patients and reviewed by government health authorities, such as completing major clinical trials, filing safety and effectiveness data, or receiving marketing approval. Investors watch these checkpoints like milestones on a roadmap because each one sharply changes the odds that a product will reach patients and generate revenue, much like a car passing inspection before it can be sold.

contingent right financial

"Each performance share unit represented a contingent right to receive one common share"

FAQ

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

What insider transaction did DFTX report for Chief Medical Officer Daniel Karlin?

Definium Therapeutics reported that Chief Medical Officer Daniel Karlin received a grant of 200,000 common shares on September 14, 2026, classified as a grant or award acquisition at a reported price of $0.00 per share, linked to previously granted performance share units.

How many DFTX shares does Daniel Karlin hold after this Form 4 transaction?

After the reported grant, Daniel Karlin directly holds 803,699 common shares of Definium Therapeutics. This total includes 417 shares acquired under the 2024 Employee Share Purchase Plan on August 17, 2026, as described in the filing footnotes.

What are the vesting conditions for Daniel Karlin’s 200,000 DFTX performance-based shares?

The 200,000 common shares represent the third tranche of performance share units that remain subject to vesting based on Dr. Karlin’s continued employment through March 12, 2028 and the achievement of specified clinical and regulatory milestones in the Performance Share Unit Award Agreement.

When were the performance share units underlying this DFTX grant originally granted?

The performance share units underlying this grant were originally granted effective March 12, 2025. The 200,000 common shares reported on this Form 4 are identified as the third tranche of that performance share unit award.

Were the reported DFTX insider transactions made under a Rule 10b5-1 trading plan?

No. The Form 4 indicates that the Rule 10b5-1 checkbox is not marked, and no footnote states that the transactions were made pursuant to a Rule 10b5-1 trading plan or other pre-arranged trading arrangement.

What additional DFTX shares did Daniel Karlin acquire through the 2024 Employee Share Purchase Plan?

The filing notes that Daniel Karlin’s total holdings include 417 shares acquired under the Definium Therapeutics, Inc. 2024 Employee Share Purchase Plan on August 17, 2026, which are part of his reported 803,699 directly held common shares.

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

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Available on EDGAR 09/14/2026 - 08:30 AM Accepted by SEC EDGAR 09/14/2026 - 08:30 AM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Karlin Daniel

(Last) (First) (Middle)

C/O DEFINIUM THERAPEUTICS, INC.

ONE WORLD TRADE CENTER, SUITE 8500

(Street)

NEW YORK NEW YORK 10007

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Definium Therapeutics, Inc. [ DFTX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Medical Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/14/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Shares	09/14/2026		A		200,000(1)	A	$0.00	803,699(2)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The common shares represent the third tranche of performance share units granted effective March 12, 2025, and remain subject to vesting based on the Reporting Person's continued employment through March 12, 2028. Each performance share unit represented a contingent right to receive one common share based on, and subject to, the achievement of certain clinical and regulatory milestones set forth in the Performance Share Unit Award Agreement.

2. Amount includes 417 shares acquired under the Definium Therapeutics, Inc. 2024 Employee Share Purchase Plan on August 17, 2026.

	/s/Mark Sullivan, Attorney-in-Fact for Dan Karlin	09/14/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)