C4 Therapeutics CMO reports RSU vesting, share withholding

Rhea-AI Filing Summary

C4 Therapeutics, Inc. reported equity compensation activity for Chief Medical Officer Leonard Reyno. On July 10, 2026, Reyno acquired 15,325 shares of common stock upon vesting of previously granted restricted stock units. In a related move, 7,397 shares were withheld by the company to cover tax obligations associated with this vesting, which the company states does not represent an open-market sale.

Filing Explained

On 2026-07-10, RSU vesting and tax withholding changed the insider's direct holding to 372,406 shares, without a disclosed holder-level structural effect.

This Form 4 reports completed transactions on 2026-07-10: the reporting person acquired 15,325 common shares upon vesting of previously disclosed restricted stock units and reported 372,406 common shares held directly afterward.

The filing also reports that 7,397 shares were withheld to satisfy tax obligations connected with the vesting and settlement, and expressly states that this was not a sale by the reporting person.

Form 4 reports an insider transaction within two business days; its code definitions identify M as an option or derivative exercise and F as shares withheld to cover taxes on vesting, while the filing's footnotes describe the M-coded event specifically as RSU vesting.

The supplied evidence supports a change in the reporting person's holdings, but does not disclose a case-specific structural consequence for the issuer or its existing common holders.

Insider Trade Summary

Net Buyer: 7,928 shares

Net Buy 2 txns

Insider REYNO LEONARD

Role Chief Medical Officer

Type	Security	Shares	Price	Value
Exercise	Common Stock F1	15,325	$0.00	$0.00
Tax Withholding	Common Stock F2	7,397	$4.06	$30K

Holdings After Transaction: Common Stock — 372,406 shares (Direct)

Footnotes (2)

1. F1. Reflects the acquisition of shares of Common Stock upon vesting of previously disclosed grants of restricted stock units ("RSUs"). The grant of RSUs was initially reported in Table I of the Form 4 filed by the Reporting Person on July 12, 2023.
2. F2. Represents shares withheld by the Issuer to satisfy tax withholding obligations in connection with the vesting and settlement of RSUs and does not represent a sale by the Reporting Person.

Key Figures

Shares acquired via RSU vesting: 15,325 shares of Common Stock Shares withheld for taxes: 7,397 shares of Common Stock Tax withholding price: $4.06 per share +2 more

5 metrics

Shares acquired via RSU vesting 15,325 shares of Common Stock Acquisition upon vesting of previously granted RSUs on July 10, 2026

Shares withheld for taxes 7,397 shares of Common Stock Withheld by issuer to satisfy tax obligations related to RSU vesting

Tax withholding price $4.06 per share Transaction price per share for 7,397 withheld shares

Holdings after acquisition entry 379,803 shares Total shares reported following the RSU-related acquisition transaction row

Holdings after tax-withholding entry 372,406 shares Total shares reported following the tax-withholding disposition transaction row

Key Terms

restricted stock units ("RSUs"), tax withholding obligations, vesting and settlement, Exercise or conversion of derivative security

4 terms

restricted stock units ("RSUs") financial

"Reflects the acquisition of shares of Common Stock upon vesting of previously disclosed grants of restricted stock units ("RSUs")."

Restricted stock units (RSUs) are a company promise to give an employee shares of stock (or cash equivalent) in the future, but only after certain conditions—usually staying with the company for a set time or hitting performance goals—are met. Investors watch RSUs because when they vest they increase the number of shares outstanding and can lead insiders to sell shares, affecting share price, company dilution and the true cost of employee pay.

tax withholding obligations financial

"Represents shares withheld by the Issuer to satisfy tax withholding obligations in connection with the vesting and settlement of RSUs."

vesting and settlement financial

"to satisfy tax withholding obligations in connection with the vesting and settlement of RSUs"

Exercise or conversion of derivative security financial

"transaction_code_description": "Exercise or conversion of derivative security""

FAQ

What did C4 Therapeutics (CCCC) Chief Medical Officer Leonard Reyno report on this Form 4?

Leonard Reyno reported vesting of restricted stock units resulting in the acquisition of 15,325 shares of C4 Therapeutics common stock, with a portion of those shares withheld to cover associated tax obligations.

How many C4 Therapeutics (CCCC) shares did Leonard Reyno acquire through RSU vesting?

Leonard Reyno acquired 15,325 shares of C4 Therapeutics common stock upon vesting of previously granted restricted stock units, as referenced to a grant initially reported on a prior Form 4 filed on July 12, 2023.

How many C4 Therapeutics (CCCC) shares were withheld for taxes in this Form 4?

A total of 7,397 shares of C4 Therapeutics common stock were withheld by the issuer to satisfy tax withholding obligations related to the vesting and settlement of RSUs, which the company notes does not represent a sale by Leonard Reyno.

At what price were the withheld C4 Therapeutics (CCCC) shares valued for tax purposes?

The 7,397 withheld shares were valued at $4.06 per share for tax-withholding purposes, based on the transaction price per share reported in the Form 4 for the tax-withholding disposition on July 10, 2026.

Does Leonard Reyno’s C4 Therapeutics (CCCC) Form 4 show any open-market stock sales?

No open-market sales are shown. The filing states the 7,397-share disposition represents shares withheld by C4 Therapeutics to satisfy tax withholding obligations and explicitly notes this does not represent a sale by Leonard Reyno.

How many C4 Therapeutics (CCCC) shares does Leonard Reyno hold after these transactions?

Following the reported transactions, one line shows Reyno holding 379,803 shares after the acquisition and another shows 372,406 shares after the tax-withholding entry, each figure tied to its respective transaction row in the Form 4.

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Available on EDGAR 07/13/2026 - 04:34 PM Accepted by SEC EDGAR 07/13/2026 - 04:33 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).

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^*

REYNO LEONARD

(Last) (First) (Middle)

C/O C4 THERAPEUTICS, INC.

490 ARSENAL WAY #120

(Street)

WATERTOWN MASSACHUSETTS 02472

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
C4 Therapeutics, Inc. [ CCCC ]

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)
07/10/2026

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 Stock	07/10/2026		M(1)	V	15,325	A	$0	379,803	D
Common Stock	07/10/2026		F(2)		7,397	D	$4.06	372,406	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. Reflects the acquisition of shares of Common Stock upon vesting of previously disclosed grants of restricted stock units ("RSUs"). The grant of RSUs was initially reported in Table I of the Form 4 filed by the Reporting Person on July 12, 2023.

2. Represents shares withheld by the Issuer to satisfy tax withholding obligations in connection with the vesting and settlement of RSUs and does not represent a sale by the Reporting Person.

Remarks:

	/s/ Shagha Russell, Attorney-in-Fact	07/13/2026
	** 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)