Definium CLO granted 125K performance shares

Definium Therapeutics’ Chief Legal Officer received 125,000 performance-based shares that vest through March 12, 2028, tied to employment and milestone conditions.

Rhea-AI Filing Summary

Definium Therapeutics, Inc. (DFTX) reported that its Chief Legal Officer, Mark Sullivan, acquired 125,000 common shares on September 14, 2026 as a grant of performance share units. These shares represent the third tranche of units granted effective March 12, 2025 and remain subject to vesting based on his continued employment through March 12, 2028 and achievement of specified clinical and regulatory milestones. Following this grant, Sullivan holds 508,279 common shares directly, including 208 shares previously acquired under the company’s 2024 Employee Share Purchase Plan. No Rule 10b5-1 trading plan is reported for this award.

Insider Trade Summary

Grant/Award: 125,000 shares

Grant/Award 1 txn

Insider Sullivan Mark

Role Chief Legal Officer

Type	Security	Shares	Price	Value
Grant/Award	Common Shares F1, F2	125,000	$0.00	$0.00

Holdings After Transaction: Common Shares — 508,279 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 208 shares acquired under the Definium Therapeutics, Inc. 2024 Employee Share Purchase Plan on August 17, 2026.

Key Figures

Performance share units granted: 125,000 shares Shares held after transaction: 508,279 shares Shares from Employee Share Purchase Plan: 208 shares +3 more

6 metrics

Performance share units granted 125,000 shares Grant of common shares on September 14, 2026 representing third tranche of PSUs

Shares held after transaction 508,279 shares Direct common share holdings by Mark Sullivan following the September 14, 2026 grant

Shares from Employee Share Purchase Plan 208 shares Common shares acquired under the 2024 Employee Share Purchase Plan on August 17, 2026

Grant price per share $0.00 per share Reported price for the 125,000 performance-based common shares granted

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

Original PSU grant effective date March 12, 2025 Effective date of the performance share unit award of which this is the third tranche

Key Terms

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

clinical and regulatory milestones medical

"subject to the achievement of certain clinical and regulatory milestones set forth"

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.

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.

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 disclose for Chief Legal Officer Mark Sullivan?

Definium Therapeutics disclosed that Chief Legal Officer Mark Sullivan acquired 125,000 common shares on September 14, 2026 through a grant of performance share units, with no cash price per share reported for the award.

How many Definium Therapeutics (DFTX) shares does Mark Sullivan own after this transaction?

After the September 14, 2026 grant, Mark Sullivan directly holds 508,279 common shares of Definium Therapeutics, Inc., which includes 208 shares previously acquired under the 2024 Employee Share Purchase Plan.

What are the vesting conditions for the 125,000 DFTX performance share units granted to Mark Sullivan?

The 125,000 shares represent the third tranche of performance share units granted effective March 12, 2025 and remain subject to vesting based on Mark Sullivan’s continued employment through March 12, 2028 and the achievement of specified clinical and regulatory milestones.

Are the new DFTX shares for Mark Sullivan tied to performance milestones?

Yes. Each performance share unit represents a contingent right to receive one common share of Definium Therapeutics, Inc., subject to achieving clinical and regulatory milestones described in the Performance Share Unit Award Agreement and continued employment through March 12, 2028.

Did Mark Sullivan’s DFTX transaction involve a Rule 10b5-1 trading plan?

No. The filing indicates that the Rule 10b5-1 checkbox is not checked, so the reported acquisition of performance share units was not made pursuant to a Rule 10b5-1 trading plan.

What additional DFTX shares did Mark Sullivan acquire under the Employee Share Purchase Plan?

The total reported holdings include 208 common shares acquired on August 17, 2026 under the Definium Therapeutics, Inc. 2024 Employee Share Purchase Plan, as noted in the footnotes.

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^*

Sullivan Mark

(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 Legal 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		125,000(1)	A	$0.00	508,279(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 208 shares acquired under the Definium Therapeutics, Inc. 2024 Employee Share Purchase Plan on August 17, 2026.

	/s/ Mark Sullivan	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)