Crescent Biopharma treasurer sells 240 shares

CBIO’s chief accounting officer sold 240 shares under a Rule 10b5-1 tax-withholding sale tied to RSU vesting, retaining 13,631 shares.

Rhea-AI Filing Summary

CRESCENT BIOPHARMA, INC. (CBIO) reported that officer Ryan Lynch, its Treasurer, Senior Vice President of Finance and Chief Accounting Officer, sold 240 Ordinary Shares on September 16, 2026 at a weighted average price of $17.90 per share in an open-market or private transaction. According to the company’s disclosure, these shares were automatically sold to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted on December 15, 2025 and were carried out under a Rule 10b5-1 instruction adopted on February 25, 2026 solely to cover taxes related to that vesting. Following this sale, Lynch directly holds 13,631 Ordinary Shares.

Insider Trade Summary 10b5-1

Net Seller: 240 shares

Net Sell 1 txn

Insider Lynch Ryan

Role See Remarks

Sold 240 shs ($4K)

Type	Security	Shares	Price	Value
Sale	Ordinary Shares F1, F2	240	$17.90	$4K

Holdings After Transaction: Ordinary Shares — 13,631 shares (Direct)

Footnotes (2)

1. F1. Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted to the Reporting Person on December 15, 2025. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the Reporting Person on February 25, 2026, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.
2. F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $17.10 to $19.17, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price at which the transactions were effected.

Key Figures

Shares sold: 240 shares Weighted average sale price: $17.90 per share Sale price range: $17.10–$19.17 per share +3 more

6 metrics

Shares sold 240 shares Ordinary Shares sold on September 16, 2026

Weighted average sale price $17.90 per share Average price for the 240 shares sold on September 16, 2026

Sale price range $17.10–$19.17 per share Range of prices across multiple sale transactions

Shares held after transaction 13,631 shares Direct ownership by Ryan Lynch following the sale

RSU grant date December 15, 2025 Restricted stock units whose vesting triggered tax-withholding sale

Rule 10b5-1 instruction adoption date February 25, 2026 Date Lynch adopted the trading instruction covering these tax-related sales

Key Terms

Rule 10b5-1 instruction, restricted stock units, weighted average price, tax withholding obligations

4 terms

Rule 10b5-1 instruction regulatory

"The sales were effected pursuant to a Rule 10b5-1 instruction adopted"

restricted stock units financial

"in connection with the settlement of restricted stock units granted"

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.

weighted average price financial

"The price reported in Column 4 is a weighted average price"

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

tax withholding obligations financial

"sold by the Reporting Person to satisfy tax withholding obligations"

FAQ

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

What insider transaction did CBIO disclose for Ryan Lynch on September 16, 2026?

CBIO disclosed that Ryan Lynch sold 240 Ordinary Shares on September 16, 2026 in a sale reported as an open-market or private transaction, primarily to satisfy tax withholding obligations tied to vested restricted stock units.

At what price were the CBIO shares sold in Ryan Lynch’s Form 4 filing?

The filing reports a weighted average price of $17.90 per share. A footnote explains the shares were sold in multiple transactions at prices ranging from $17.10 to $19.17, inclusive.

How many CBIO shares does Ryan Lynch hold after this reported sale?

After the reported sale, Ryan Lynch directly holds 13,631 Ordinary Shares of Crescent Biopharma, Inc., as stated in the Form 4 disclosure.

Was Ryan Lynch’s CBIO share sale made under a Rule 10b5-1 trading plan?

Yes. The disclosure states the sales were effected pursuant to a Rule 10b5-1 instruction adopted by Ryan Lynch on February 25, 2026, with the stated intent solely to cover taxes related to the vesting of restricted stock units.

Why were CBIO shares sold in Ryan Lynch’s September 2026 Form 4?

A footnote explains the 240 shares were automatically sold to satisfy tax withholding obligations arising from the settlement of restricted stock units granted to Ryan Lynch on December 15, 2025.

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

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Available on EDGAR 09/18/2026 - 04:04 PM Accepted by SEC EDGAR 09/18/2026 - 04:03 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^*

Lynch Ryan

(Last) (First) (Middle)

C/O CRESCENT BIOPHARMA, INC.

300 FIFTH AVENUE

(Street)

WALTHAM MASSACHUSETTS 02451

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
CRESCENT BIOPHARMA, INC. [ CBIO ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	See Remarks

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/16/2026

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
Ordinary Shares	09/16/2026		S		240(1)	D	$17.9(2)	13,631	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 shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted to the Reporting Person on December 15, 2025. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction adopted by the Reporting Person on February 25, 2026, solely with the intent to cover taxes in connection with the vesting of the restricted stock units.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $17.10 to $19.17, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price at which the transactions were effected.

Remarks:

Treasurer, Senior Vice President of Finance and Chief Accounting Officer.

	/s/ Barbara Bispham Hale, as attorney-in-fact for Ryan Lynch	09/18/2026
	** 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)