Definium Therapeutics (DFTX) CLO granted 125,000 RSUs in Form 4

Rhea-AI Filing Summary

Definium Therapeutics, Inc. Chief Legal Officer Mark Sullivan reported an equity award of 125,000 common shares in the form of restricted stock units on February 3, 2026. The award was granted at a price of $0.00 per share as part of his compensation.

Each RSU represents a right to receive one common share, vesting in 16 equal quarterly installments beginning June 1, 2026, so long as he continues providing service on each vesting date. Following this grant, he beneficially owns 407,576 common shares directly.

Insights

Equity compensation and insider-transactions analyst

Routine RSU grant to Definium’s CLO with time-based vesting.

The Chief Legal Officer of Definium Therapeutics, Mark Sullivan, received 125,000 restricted stock units valued at $0.00 per share as an equity award. RSUs are a common form of long-term incentive tying executive compensation to future company performance through share ownership.

The RSUs vest in 16 equal quarterly installments starting on June 1, 2026, contingent on continued service. This structure encourages retention over four years and aligns incentives with the company’s longer-term trajectory, but actual realized value will depend on future share price and his ongoing employment.

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 NY 10007

(City) (State) (Zip)

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

3. Date of Earliest Transaction (Month/Day/Year)
02/03/2026

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

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

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

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	02/03/2026		A		125,000(1)	A	$0.00	407,576	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. These shares represent restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one common share of the Issuer. The RSUs vest in 16 equal quarterly installments beginning on June 1, 2026, subject to the Reporting Person providing continuous service to the Issuer on each such vesting date.

	/s/ Mark Sullivan	02/05/2026
	** 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.

FAQ

What insider transaction did Definium Therapeutics (DFTX) report for Mark Sullivan?

Definium Therapeutics reported that Chief Legal Officer Mark Sullivan received an award of 125,000 restricted stock units. Each RSU represents one common share, granted at $0.00 per share as equity compensation, increasing his beneficial ownership to 407,576 common shares directly.

How many Definium Therapeutics (DFTX) shares does Mark Sullivan own after this Form 4?

After the reported transaction, Mark Sullivan beneficially owns 407,576 Definium Therapeutics common shares directly. This total includes 125,000 newly granted restricted stock units that convert into shares as they vest over time, subject to his continued service with the company.

What are the terms of the 125,000 RSUs granted by Definium Therapeutics (DFTX)?

The 125,000 RSUs each represent a right to receive one Definium common share. They vest in 16 equal quarterly installments beginning June 1, 2026, and vesting on each date depends on Mark Sullivan continuing to provide service to the company at that time.

When do Mark Sullivan’s Definium Therapeutics (DFTX) RSUs start vesting?

The RSUs granted to Mark Sullivan start vesting on June 1, 2026. Vesting then continues in 16 equal quarterly installments, effectively over four years, as long as he continues to provide services to Definium Therapeutics on each scheduled vesting date.

Was there any cash paid for the RSUs reported in the Definium Therapeutics (DFTX) Form 4?

No cash was paid for the RSUs; they were granted at a price of $0.00 per share. This reflects a typical equity compensation grant, where value comes from future delivery of common shares if vesting conditions are satisfied over time.

What role does Mark Sullivan hold at Definium Therapeutics (DFTX) in this Form 4?

In this Form 4, Mark Sullivan is identified as an officer of Definium Therapeutics, serving as Chief Legal Officer. His position explains why he receives equity compensation in the form of restricted stock units, aligning his interests with the company’s long-term performance.