C4 Therapeutics holder plans sale of 19,519 shares

Rhea-AI Filing Summary

A holder of C4 Therapeutics, Inc. (CCCC) common stock filed a Form 144 notice to sell up to 19,519 shares of common stock through Morgan Stanley Smith Barney LLC Executive Financial Services, with an aggregate market value of $76,680.39, in connection with a stock option exercise for cash expected on August 12, 2026. The notice also reports that Mark Mossler previously sold 9,087 shares of common stock on May 27, 2026 for an aggregate market value of $35,484.74.

Key Figures

Shares to be sold: 19,519 shares Aggregate market value of planned sale: $76,680.39 Planned sale date: 08/12/2026 +2 more

5 metrics

Shares to be sold 19,519 shares Common stock listed for proposed sale in connection with a stock option exercise

Aggregate market value of planned sale $76,680.39 Market value associated with 19,519 common shares to be sold

Planned sale date 08/12/2026 Date tied to the stock option exercise and proposed sale for cash

Prior shares sold 9,087 shares Common stock sold on 05/27/2026 during the past three months

Aggregate market value of prior sale $35,484.74 Market value for 9,087 common shares sold on 05/27/2026

Key Terms

Form 144, Securities To Be Sold, Stock Option Exercise

3 terms

Form 144 regulatory

"A holder of C4 Therapeutics, Inc. (CCCC) common stock filed a Form 144 notice"

Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.

Securities To Be Sold regulatory

"144: Securities To Be Sold Common | 08/12/2026 | Stock Option Exercise"

Stock Option Exercise financial

"Common | 08/12/2026 | Stock Option Exercise | Issuer | | | 19519"

A stock option exercise is the act of using a previously granted right to buy shares of a company's stock at a specific, predetermined price by paying that price and receiving the shares. It matters to investors because exercising changes who owns the shares (which can dilute existing ownership), can trigger taxable events and shift potential gains or losses, and affects voting power and the company’s outstanding share count—like turning a voucher into an actual product that becomes part of circulating supply.

FAQ

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

What does CCCC’s latest Form 144 filing disclose?

The Form 144 filing for CCCC discloses a planned sale of up to 19,519 common shares, valued at $76,680.39, in connection with a stock option exercise expected on August 12, 2026.

How many CCCC shares are planned to be sold under this Form 144?

The filing lists a proposed sale of up to 19,519 shares of C4 Therapeutics, Inc. common stock. These shares are associated with a stock option exercise and are to be sold for cash on or after August 12, 2026.

What is the aggregate market value of the CCCC shares to be sold?

The aggregate market value of the 19,519 C4 Therapeutics, Inc. shares listed for sale is $76,680.39. This value appears in the Form 144 under the securities information section tied to the planned stock option exercise.

Who is the selling security holder in the CCCC Form 144 and what were recent sales?

The Form 144 identifies Mark Mossler as a selling holder and notes a prior sale of 9,087 common shares on May 27, 2026 for an aggregate market value of $35,484.74 during the past three months.

Which broker is handling the planned CCCC share sale in the Form 144?

The planned sale of C4 Therapeutics, Inc. common stock is to be handled through Morgan Stanley Smith Barney LLC Executive Financial Services, located at 1 New York Plaza, 8th Floor, New York, NY 10004, as listed in the filing.

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

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Available on EDGAR 08/12/2026 - 05:31 PM Accepted by SEC EDGAR 08/12/2026 - 05:31 PM Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001992219
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	C4 THERAPEUTICS, INC.
SEC File Number	001-39567
Address of Issuer	490 Arsenal Way, Suite 120 Watertown MASSACHUSETTS 02472
Phone	(617) 231-0700
Name of Person for Whose Account the Securities are To Be Sold	Mark Mossler
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	19519	76680.39	123025136	08/12/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	08/12/2026	Stock Option Exercise	Issuer			19519	08/12/2026	Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Mark Mossler 490 Arsenal Way, Suite 120 Watertown MA 02472	Common	05/27/2026	9087	35484.74

144: Remarks and Signature

Remarks
Date of Notice	08/12/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Mark Mossler
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)