C4 Therapeutics, Inc. has a significant shareholder group led by Squadron Master Fund LP and related parties reporting beneficial ownership of 7,600,000 shares of common stock. This position consists of 7,200,000 shares plus 400,000 shares underlying currently exercisable long call options held by Squadron Capital Management LLC.
The reported holdings represent approximately 6.9% of C4 Therapeutics’ common stock, based on 110,567,222 shares outstanding as of May 1, 2026, plus the option shares. Voting and dispositive powers over all 7,600,000 shares are reported as shared among Squadron Master Fund LP, Squadron Capital Management LLC, and partners Matthew Sesterhenn and William Blank, who each disclaim beneficial ownership beyond their indirect roles.
Positive
None.
Negative
None.
Key Figures
Beneficial ownership:7,600,000 sharesOwnership percentage:6.9%Outstanding shares baseline:110,567,222 shares+2 more
5 metrics
Beneficial ownership7,600,000 sharesShares of C4 Therapeutics common stock reported as beneficially owned by Squadron-related filers
Ownership percentage6.9%Portion of C4 Therapeutics common stock represented by 7,600,000 shares
Outstanding shares baseline110,567,222 sharesC4 Therapeutics common shares outstanding as of May 1, 2026, used for ownership calculation
Shares from options400,000 sharesCommon shares underlying currently exercisable long call options held by Squadron Capital Management LLC
Common shares held7,200,000 sharesPortion of the 7,600,000 total consisting of C4 Therapeutics common stock (excluding option shares)
Key Terms
beneficial owner, shared voting power, shared dispositive power, Investment Advisers Act of 1940, +1 more
5 terms
beneficial ownerfinancial
"may be deemed to be the beneficial owner of all shares of Common Stock"
A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.
shared voting powerfinancial
"Shared Voting Power 7,600,000.00"
Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.
shared dispositive powerfinancial
"Shared Dispositive Power 7,600,000.00"
Investment Advisers Act of 1940regulatory
"an investment adviser that is registered under the Investment Advisers Act of 1940"
A U.S. federal law that sets rules for people and firms who give investment advice, requiring them to register with regulators, be honest about conflicts, keep records, and follow basic standards of care. It matters to investors because those rules act like licensing and consumer protections — similar to having safety standards for a mechanic — helping ensure advisers act in clients’ financial interests and reducing the risk of fraud or misuse of funds.
long call optionsfinancial
"400,000 shares of Common Stock underlying long call options held by Squadron Capital"
FAQ
What percentage of C4 Therapeutics (CCCC) does Squadron report owning?
Squadron-related entities report beneficial ownership of 6.9% of C4 Therapeutics’ common stock. This is based on 110,567,222 shares outstanding as of May 1, 2026, plus 400,000 shares issuable upon exercise of long call options.
How many C4 Therapeutics (CCCC) shares does Squadron beneficially own?
Squadron-related entities report beneficial ownership of 7,600,000 C4 Therapeutics common shares. This includes 7,200,000 shares of common stock plus 400,000 shares underlying currently exercisable long call options held by Squadron Capital Management LLC.
Who are the reporting persons in the C4 Therapeutics (CCCC) Schedule 13G/A?
The reporting persons are Squadron Master Fund LP, Squadron Capital Management, LLC, and individuals Matthew Sesterhenn and William Blank. Squadron Capital Management acts as investment adviser to the funds that hold the C4 Therapeutics shares.
What portion of C4 Therapeutics (CCCC) shares are tied to options in this 13G/A?
Of the reported 7,600,000 shares, 400,000 shares are underlying currently exercisable long call options held by Squadron Capital Management LLC. The remaining 7,200,000 shares are common stock already outstanding and held by the funds.
Do Squadron and its principals have sole or shared voting power over C4 Therapeutics (CCCC) shares?
The reporting persons indicate 0 shares with sole voting power and 7,600,000 shares with shared voting power. They likewise report shared dispositive power over 7,600,000 shares and expressly disclaim beneficial ownership beyond their advisory roles.
What share count did C4 Therapeutics (CCCC) report outstanding for this 13G/A calculation?
The 6.9% ownership figure is based on 110,567,222 C4 Therapeutics common shares outstanding as of May 1, 2026, as reported by the company, plus 400,000 shares issuable upon exercise of Squadron’s call options.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 1)
C4 Therapeutics, Inc.
(Name of Issuer)
Common Stock, $0.0001 par value per share
(Title of Class of Securities)
12529R107
(CUSIP Number)
06/30/2026
(Date of Event Which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
Rule 13d-1(b)
Rule 13d-1(c)
Rule 13d-1(d)
schemaVersion:
SCHEDULE 13G
CUSIP Number(s):
12529R107
1
Names of Reporting Persons
Squadron Master Fund LP
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
7,600,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
7,600,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
7,600,000.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
6.9 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP Number(s):
12529R107
1
Names of Reporting Persons
Squadron Capital Management LLC
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
7,600,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
7,600,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
7,600,000.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
6.9 %
12
Type of Reporting Person (See Instructions)
IA, HC
SCHEDULE 13G
CUSIP Number(s):
12529R107
1
Names of Reporting Persons
Matthew Sesterhenn
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
7,600,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
7,600,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
7,600,000.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
6.9 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
CUSIP Number(s):
12529R107
1
Names of Reporting Persons
William Blank
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
7,600,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
7,600,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
7,600,000.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
6.9 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
C4 Therapeutics, Inc.
(b)
Address of issuer's principal executive offices:
490 ARSENAL WAY, SUITE 120, WATERTOWN, MASSACHUSETTS, 02472.
Item 2.
(a)
Name of person filing:
Squadron Master Fund LP
Squadron Capital Management, LLC
Matthew Sesterhenn
William Blank
(b)
Address or principal business office or, if none, residence:
Squadron Master Fund LP
c/o Squadron Capital Management, LLC
1211 West 22nd Street, Suite 1008
Oak Brook, IL 60523
Squadron Capital Management, LLC
1211 West 22nd Street, Suite 1008
Oak Brook, IL 60523
Matthew Sesterhenn
c/o Squadron Capital Management, LLC
1211 West 22nd Street, Suite 1008
Oak Brook, IL 60523
William Blank
c/o Squadron Capital Management, LLC
1211 West 22nd Street, Suite 1008
Oak Brook, IL 60523
(c)
Citizenship:
Squadron Master Fund LP - Delaware
Squadron Capital Management, LLC - Delaware
Matthew Sesterhenn - United States
William Blank - United States
(d)
Title of class of securities:
Common Stock, $0.0001 par value per share
(e)
CUSIP No.:
12529R107
Item 3.
If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)
Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)
Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)
Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)
Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)
An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)
An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)
A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)
A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)
A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)
A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
(k)
Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.
Ownership
(a)
Amount beneficially owned:
Squadron Capital Management, LLC is an investment adviser that is registered under the Investment Advisers Act of 1940. Squadron Capital Management, LLC, which serves as investment adviser to private funds, including but not limited to Squadron Master Fund LP (collectively, the "Funds"), may be deemed to be the beneficial owner of all shares of Common Stock held by the Funds. Mr. Sesterhenn and Mr. Blank, as Partners of Squadron Capital Management, LLC, with the power to exercise investment and voting discretion, may be deemed to be the beneficial owner of all shares of Common Stock held by the Funds. Pursuant to Rule 13d-4 under the Securities Exchange Act of 1934, as amended, Squadron Capital Management, LLC and Mr. Sesterhenn and Mr. Blank expressly disclaim beneficial ownership over any of the securities reported in this statement, and the filing of this statement shall not be construed as an admission that Squadron Capital Management, LLC or Mr. Sesterhenn and Mr. Blank are the beneficial owner of any of the securities reported herein.
This amount comprises beneficial ownership of 7,600,000 shares of Common Stock which consists of (i) 7,200,000 shares of Common Stock and (ii) 400,000 shares of Common Stock underlying long call options held by Squadron Capital Management LLC that are currently exercisable (the "Options").
Squadron Master Fund LP - 7,600,000 shares
Squadron Capital Management, LLC - 7,600,000 shares
Matthew Sesterhenn - 7,600,000 shares
William Blank - 7,600,000 shares
(b)
Percent of class:
All such shares of Common Stock in the aggregate represent beneficial ownership of approximately 6.9% of the Common Stock based on (i) 110,567,222 shares of Common Stock outstanding, $0.0001 par value per share, as of May 1, 2026, as reported by the Issuer on Form 10-Q filed with the Securities and Exchange Commission on May 12, 2026, plus (ii) 400,000 shares of Common Stock issuable upon exercise of the Options.
Squadron Master Fund LP - 6.9%
Squadron Capital Management, LLC - 6.9%
Matthew Sesterhenn - 6.9%
William Blank - 6.9%
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
Squadron Master Fund LP - 0
Squadron Capital Management, LLC - 0
Matthew Sesterhenn - 0
William Blank - 0
(ii) Shared power to vote or to direct the vote:
Squadron Master Fund LP - 7,600,000 shares
Squadron Capital Management, LLC - 7,600,000 shares
Matthew Sesterhenn - 7,600,000 shares
William Blank - 7,600,000 shares
(iii) Sole power to dispose or to direct the disposition of:
Squadron Master Fund LP - 0
Squadron Capital Management, LLC - 0
Matthew Sesterhenn - 0
William Blank - 0
(iv) Shared power to dispose or to direct the disposition of:
Squadron Master Fund LP - 7,600,000 shares
Squadron Capital Management, LLC - 7,600,000 shares
Matthew Sesterhenn - 7,600,000 shares
William Blank - 7,600,000 shares
Item 5.
Ownership of 5 Percent or Less of a Class.
Not Applicable
Item 6.
Ownership of more than 5 Percent on Behalf of Another Person.
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.
The Funds have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the shares of Common Stock covered by this Statement.
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary.
See Notes above.
Item 8.
Identification and Classification of Members of the Group.
Not Applicable
Item 9.
Notice of Dissolution of Group.
Not Applicable
Item 10.
Certifications:
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.
SIGNATURE
After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.
Squadron Master Fund LP
Signature:
/s/ Matthew Sesterhenn
Name/Title:
Partner, Squadron Partners LLC, its General Partner
