Definium CMO sells shares to cover tax on RSUs

Definium Therapeutics, Inc. Chief Medical Officer Karlin Daniel sold 10,035 Common Shares of DFTX on June 25, 2026 at an average price of $45.03 per share.

Rhea-AI Filing Summary

Definium Therapeutics, Inc. Chief Medical Officer Karlin Daniel sold 10,035 Common Shares of DFTX on June 25, 2026 at an average price of $45.03 per share. A footnote explains the shares were sold to satisfy withholding tax obligations upon settlement of vested restricted stock units under sell-to-cover elections in a Rule 10b5-1 plan adopted on June 14, 2022. Following this tax-related transaction, Daniel directly holds 503,282 Common Shares.

Insider Trade Summary 10b5-1

Net Seller: 10,035 shares

Net Sell 1 txn

Insider Karlin Daniel

Role Chief Medical Officer

Sold 10,035 shs ($452K)

Type	Security	Shares	Price	Value
Sale	Common Shares	10,035	$45.03	$452K

Holdings After Transaction: Common Shares — 503,282 shares (Direct)

Footnotes (1)

1. F1. Represents the number of Common Shares sold to satisfy withholding tax obligations in connection with the settlement of vested restricted stock units, pursuant to sell-to-cover elections under a Rule 10b5-1 plan adopted on June 14, 2022.

Key Figures

Shares sold: 10,035 shares Sale price: $45.03 per share Shares after transaction: 503,282 shares +1 more

4 metrics

Shares sold 10,035 shares Common Shares sold on June 25, 2026

Sale price $45.03 per share Average price for Common Shares sold

Shares after transaction 503,282 shares Direct holdings following June 25, 2026 sale

Plan adoption date June 14, 2022 Adoption date of Rule 10b5-1 sell-to-cover plan

Key Terms

restricted stock units, withholding tax obligations, sell-to-cover elections, Rule 10b5-1 plan

4 terms

restricted stock units financial

"in connection with the settlement of vested restricted stock units, pursuant"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

withholding tax obligations financial

"Common Shares sold to satisfy withholding tax obligations in connection"

sell-to-cover elections financial

"vested restricted stock units, pursuant to sell-to-cover elections under"

Rule 10b5-1 plan regulatory

"sell-to-cover elections under a Rule 10b5-1 plan adopted on June 14, 2022"

A Rule 10b5-1 plan is a prearranged, written schedule that lets corporate insiders buy or sell company stock at set times or amounts, even if they later learn material nonpublic information. Think of it like setting an automatic thermostat for trades: it creates a clear record that trades were planned in advance, reducing the risk of insider-trading accusations and helping investors trust that insider transactions are routine rather than based on secret information.

FAQ

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

What insider transaction did Definium Therapeutics (DFTX) report for Karlin Daniel?

Definium Therapeutics reported that Chief Medical Officer Karlin Daniel sold 10,035 Common Shares. The sale occurred on June 25, 2026 and was tied to tax withholding related to vested restricted stock units under a pre-arranged Rule 10b5-1 sell-to-cover plan.

How many Definium Therapeutics (DFTX) shares did Karlin Daniel sell and at what price?

Karlin Daniel sold 10,035 Common Shares of Definium Therapeutics at an average price of $45.03 per share. The transaction was used to cover withholding tax obligations triggered by the settlement of vested restricted stock units, rather than a discretionary open-market sale.

Were Karlin Daniel’s Definium Therapeutics (DFTX) share sales under a Rule 10b5-1 plan?

Yes, the share sale was executed pursuant to a Rule 10b5-1 plan adopted on June 14, 2022. The footnote states the transaction followed sell-to-cover elections, meaning the timing and mechanics were pre-arranged to handle tax obligations from vesting restricted stock units.

Why did Karlin Daniel sell Definium Therapeutics (DFTX) shares in this Form 4 filing?

The filing states the 10,035 shares were sold to satisfy withholding tax obligations. These taxes arose from the settlement of vested restricted stock units, and the sale followed sell-to-cover elections under a pre-established Rule 10b5-1 trading plan, indicating a tax-driven, mechanistic transaction.

How many Definium Therapeutics (DFTX) shares does Karlin Daniel hold after this transaction?

After the June 25, 2026 transaction, Karlin Daniel directly holds 503,282 Common Shares of Definium Therapeutics. This post-transaction balance in the Form 4 shows he retained a substantial equity position despite the tax-related sale of 10,035 shares to cover withholding obligations.

Is Karlin Daniel’s Definium Therapeutics (DFTX) share sale a routine tax withholding event?

The footnote indicates the sale represents shares sold to satisfy withholding tax obligations from vested restricted stock units. Because it occurred under sell-to-cover elections in a Rule 10b5-1 plan, it appears as a routine, tax-driven event rather than a discretionary reduction of his ownership stake.

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

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Accepted by SEC EDGAR 06/26/2026 - 04:30 PM 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).

X

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)
06/25/2026

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	06/25/2026		S(1)		10,035	D	$45.03	503,282	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. Represents the number of Common Shares sold to satisfy withholding tax obligations in connection with the settlement of vested restricted stock units, pursuant to sell-to-cover elections under a Rule 10b5-1 plan adopted on June 14, 2022.

	/s/Mark Sullivan, Attorney-in-Fact for Dan Karlin	06/26/2026
	** 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)