Definium Therapeutics (DFTX) CFO disposes 3,013 shares to cover RSU taxes

Rhea-AI Filing Summary

Definium Therapeutics Chief Financial Officer Brandi Roberts reported a small share sale tied to tax withholding. On June 25, 2026, she disposed of 3,013 common shares of Definium Therapeutics at $45.03 per share to satisfy withholding taxes from vested restricted stock units.

The transaction was executed under a previously adopted Rule 10b5-1 trading plan and represents a sell-to-cover event rather than a discretionary open-market sale. After this transaction, Roberts directly beneficially owns 209,487 common shares of the company.

Key Figures

Shares disposed: 3,013 shares Sale price: $45.03 per share Post-transaction holdings: 209,487 shares +2 more

5 metrics

Shares disposed 3,013 shares Common shares sold on June 25, 2026

Sale price $45.03 per share Price for 3,013 common shares sold

Post-transaction holdings 209,487 shares Common shares beneficially owned after transaction

Transaction date 06/25/2026 Earliest transaction date reported

Plan adoption date May 30, 2025 Adoption date of Rule 10b5-1 sell-to-cover plan

Key Terms

Rule 10b5-1 plan, sell-to-cover, restricted stock units, beneficially owned

4 terms

Rule 10b5-1 plan regulatory

"pursuant to sell-to-cover elections under a Rule 10b5-1 plan adopted on May 30, 2025"

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.

sell-to-cover financial

"sold to satisfy withholding tax obligations in connection with the settlement of vested restricted stock units, pursuant to sell-to-cover elections"

Sell-to-cover is when part of newly issued or exercised company stock is immediately sold to pay required taxes and fees, so the recipient keeps the remaining shares. For investors this matters because it reduces the number of shares insiders or employees actually hold after a grant, can create small, routine share sales that aren’t signal of cashing out, and slightly increases share supply on the market—like selling a portion of a paycheck to cover the tax bill.

restricted stock units financial

"withholding tax obligations in connection with the settlement of vested restricted stock units"

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.

beneficially owned financial

"Amount of Securities Beneficially Owned Following Reported Transaction(s)"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 06/26/2026 - 04:30 PM 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^*

Roberts Brandi

(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 Financial 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)		3,013	D	$45.03	209,487	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 May 30, 2025.

	/s/ Mark Sullivan, Attorney-in-Fact for Brandi Roberts	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)

FAQ

What insider transaction did Definium Therapeutics (DFTX) report for Brandi Roberts?

Definium Therapeutics reported that CFO Brandi Roberts disposed of 3,013 common shares. The shares were sold at $45.03 each to cover withholding taxes on vested restricted stock units under a Rule 10b5-1 sell-to-cover plan.

How many Definium Therapeutics (DFTX) shares did the CFO sell and at what price?

Brandi Roberts sold 3,013 Definium Therapeutics common shares at $45.03 per share. The filing explains this sale was specifically to satisfy tax withholding obligations related to the settlement of vested restricted stock units.

Does the Definium Therapeutics (DFTX) filing indicate this was a discretionary sale?

The filing indicates the transaction was not purely discretionary. It states the 3,013 shares were sold to satisfy withholding tax obligations, pursuant to sell-to-cover elections under a Rule 10b5-1 trading plan adopted on May 30, 2025.

How many Definium Therapeutics (DFTX) shares does Brandi Roberts hold after the transaction?

After the reported transaction, Brandi Roberts beneficially owns 209,487 common shares of Definium Therapeutics. This post-transaction holding is disclosed in the Form 4 and reflects her remaining direct ownership following the 3,013-share tax-related sale.

What role does Brandi Roberts hold at Definium Therapeutics (DFTX)?

Brandi Roberts is identified as both a 10% owner and the Chief Financial Officer of Definium Therapeutics. These roles are disclosed in the Form 4, which also confirms she is the sole reporting person for the June 25, 2026 transaction.

What is the significance of the Rule 10b5-1 plan in the DFTX Form 4 filing?

The Rule 10b5-1 plan indicates the sale was prearranged. The filing notes the 3,013-share sale occurred pursuant to sell-to-cover elections under a Rule 10b5-1 plan adopted on May 30, 2025, framing it as a structured tax-withholding transaction.