Crescent Biopharma COO sells 4,570 shares for taxes

CBIO’s President and COO executed pre-planned open market share sales to cover taxes on vesting equity awards.

Rhea-AI Filing Summary

CRESCENT BIOPHARMA, INC. (CBIO) reported that President and COO Jonathan McNeill sold a total of 4,570 Ordinary Shares in open market transactions on September 16 and 18, 2026. The sales were made under a Rule 10b5-1 trading instruction adopted on February 25, 2026 and were executed solely to cover tax withholding obligations tied to vesting restricted stock units.

Insider Trade Summary 10b5-1

Net Seller: 4,570 shares

Net Sell 2 txns

Insider McNeill Jonathan

Role President and COO

Sold 4,570 shs ($77K)

Type	Security	Shares	Price	Value
Sale	Ordinary Shares F1, F2	3,839	$16.71	$64K
Sale	Ordinary Shares F1, F2	731	$17.90	$13K

Holdings After Transaction: Ordinary Shares — 134,588 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 and March 17, 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 prices reported in Column 4 are weighted average prices. These shares were sold in multiple transactions at prices ranging from $17.10 to $19.17 on September 16, 2026 and from $16.15 to $17.23 on September 18, 2026, 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 September 16, 2026: 731 shares Weighted average sale price September 16, 2026: $17.90 per share Price range September 16, 2026: $17.10–$19.17 +5 more

8 metrics

Shares sold September 16, 2026 731 shares Open market sale of Ordinary Shares

Weighted average sale price September 16, 2026 $17.90 per share Ordinary Shares sold in multiple transactions

Price range September 16, 2026 $17.10–$19.17 Range of prices for multiple transactions that day

Shares sold September 18, 2026 3,839 shares Open market sale of Ordinary Shares

Weighted average sale price September 18, 2026 $16.71 per share Ordinary Shares sold in multiple transactions

Price range September 18, 2026 $16.15–$17.23 Range of prices for multiple transactions that day

Total shares sold 4,570 shares Combined sales on September 16 and 18, 2026

Rule 10b5-1 instruction adoption date February 25, 2026 Date the trading instruction governing these sales was adopted

Key Terms

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

4 terms

Rule 10b5-1 regulatory

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

Rule 10b5-1 is a regulation that allows company insiders to buy or sell their shares at predetermined times, even if they have access to non-public information. It acts like setting a schedule in advance for transactions, helping prevent accusations of unfair trading. This rule provides a way for insiders to plan trades transparently, giving investors confidence that these transactions are not based on hidden information.

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 prices financial

"The prices reported in Column 4 are weighted average prices"

tax withholding obligations financial

"sold ... to satisfy tax withholding obligations in connection with the settlement"

FAQ

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

What insider transaction did CBIO report for Jonathan McNeill?

Jonathan McNeill, CBIO’s President and COO, reported open market sales of 4,570 Ordinary Shares on September 16 and 18, 2026. The company states these transactions were executed under a Rule 10b5-1 instruction and were solely to cover tax withholding on vesting restricted stock units.

How many CBIO shares did Jonathan McNeill sell and on which dates?

Jonathan McNeill sold 731 Ordinary Shares on September 16, 2026 and 3,839 Ordinary Shares on September 18, 2026, for a total of 4,570 shares, according to the Form 4 filing.

What were the reported sale prices for Jonathan McNeill’s CBIO share sales?

The Form 4 reports weighted average prices of $17.90 per share on September 16, 2026 and $16.71 per share on September 18, 2026. Actual individual trade prices ranged from $17.10–$19.17 and $16.15–$17.23, respectively.

Were Jonathan McNeill’s CBIO sales under a Rule 10b5-1 trading plan?

Yes. The filing states the sales were effected pursuant to a Rule 10b5-1 instruction adopted on February 25, 2026. This plan governed the transactions reported in the Form 4.

Why did Jonathan McNeill sell CBIO shares according to the Form 4?

The filing explains the sales solely covered tax withholding obligations from the settlement of restricted stock units granted on December 15, 2025 and March 17, 2025. The transactions were not described as discretionary portfolio sales.

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

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Available on EDGAR 09/18/2026 - 04:03 PM Accepted by SEC EDGAR 09/18/2026 - 04:01 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^*

McNeill Jonathan

(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)
	President and COO

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		731(1)	D	$17.9(2)	138,427	D
Ordinary Shares	09/18/2026		S		3,839(1)	D	$16.71(2)	134,588	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 and March 17, 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 prices reported in Column 4 are weighted average prices. These shares were sold in multiple transactions at prices ranging from $17.10 to $19.17 on September 16, 2026 and from $16.15 to $17.23 on September 18, 2026, 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:

Exhibit 24 - Power of Attorney

	/s/ Barbara Bispham Hale, as attorney-in-fact for Jonathan McNeill	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)