Crescent Biopharma CSO sells 658 shares at $17.90

CBIO’s chief scientific officer reported an automatic sale of shares to cover taxes tied to vesting restricted stock units under a Rule 10b5-1 instruction.

Rhea-AI Filing Summary

CRESCENT BIOPHARMA, INC. (CBIO) reported that Chief Scientific Officer Jan Pinkas sold 658 Ordinary Shares on September 16, 2026 at a weighted average price of $17.90 per share. The shares were automatically sold to satisfy tax withholding obligations upon settlement of previously granted restricted stock units, under a Rule 10b5-1 trading instruction. Following this sale, Pinkas directly holds 21,581 Ordinary Shares.

Insider Trade Summary 10b5-1

Net Seller: 658 shares

Net Sell 1 txn

Insider Pinkas Jan

Role Chief Scientific Officer

Sold 658 shs ($12K)

Type	Security	Shares	Price	Value
Sale	Ordinary Shares F1, F2	658	$17.90	$12K

Holdings After Transaction: Ordinary Shares — 21,581 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 26, 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: 658 shares Weighted average sale price: $17.90 per share Sale price range: $17.10–$19.17 per share +3 more

6 metrics

Shares sold 658 shares Ordinary Shares sold by Jan Pinkas on September 16, 2026

Weighted average sale price $17.90 per share Automatic sale to cover tax withholding on RSU settlement

Sale price range $17.10–$19.17 per share Multiple transactions comprising the reported sale

Shares held after transaction 21,581 shares Direct holdings of Jan Pinkas after the September 16, 2026 sale

RSU grant date December 15, 2025 Restricted stock units whose settlement triggered tax-related sale

Rule 10b5-1 instruction adoption date February 26, 2026 Pre-arranged instruction governing the tax-cover sales

Key Terms

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

4 terms

restricted stock units financial

"settlement of restricted stock units granted to the Reporting Person on December 15, 2025"

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.

tax withholding obligations financial

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

Rule 10b5-1 instruction regulatory

"sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 instruction"

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.

FAQ

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

What insider transaction did CBIO’s Chief Scientific Officer report on this Form 4?

The Chief Scientific Officer, Jan Pinkas, reported a sale of 658 Ordinary Shares of Crescent Biopharma, Inc. on September 16, 2026. The sale was an automatic transaction related to tax withholding on vested restricted stock units.

At what price were the CBIO shares sold in the reported transaction?

The reported sale used a weighted average price of $17.90 per share. Footnote disclosure states the shares were sold in multiple trades at prices ranging from $17.10 to $19.17 per share.

Why did the CBIO insider sell 658 shares in this Form 4 filing?

The 658 shares were automatically sold to satisfy tax withholding obligations in connection with the settlement of restricted stock units granted to Jan Pinkas on December 15, 2025. The filing states the intent was solely to cover taxes on the vesting.

Was the CBIO insider sale made under a Rule 10b5-1 trading plan?

Yes. The filing states the sales were effected pursuant to a Rule 10b5-1 instruction adopted by Jan Pinkas on February 26, 2026, with the stated intent to cover taxes related to vesting restricted stock units.

How many CBIO shares does the insider hold after this reported sale?

After the sale of 658 shares, Jan Pinkas directly holds 21,581 Ordinary Shares of Crescent Biopharma, Inc., as reported in the Form 4 following the transaction on September 16, 2026.

Does the CBIO filing provide details on the individual trade prices for the insider sale?

The filing reports a weighted average price and notes that trades occurred between $17.10 and $19.17 per share. It states that full information on the number of shares sold at each price will be provided upon request to the issuer, security holders, or SEC staff.

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 - 04:03 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^*

Pinkas Jan

(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)
	Chief Scientific Officer

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		658(1)	D	$17.9(2)	21,581	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 26, 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:

	/s/ Barbara Bispham Hale, as attorney-in-fact for Jan Pinkas	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)