Insmed (INSM) CFO reports stock sales for RSU tax withholding

Rhea-AI Filing Summary

Insmed Inc. reported that its Chief Financial Officer, Sara Bonstein, sold small blocks of common stock on three consecutive days to cover tax obligations tied to equity awards. On January 6, 2026, she sold 1,517 shares at $173.33 per share, on January 7, 2026 she sold 1,678 shares at $175.07 per share, and on January 8, 2026 she sold 1,447 shares at $174.17 per share. According to the filing, these sales were made to satisfy tax withholding obligations upon the vesting of restricted stock units and to cover related broker fees, and she directly owned 80,506 shares of common stock after the final transaction.

Insider Trade Summary

Net Seller: 4,642 shares

Net Sell 3 txns

Insider Bonstein Sara

Role Chief Financial Officer

Sold 4,642 shs ($809K)

Type	Security	Shares	Price	Value
Sale	Common Stock	1,447	$174.17	$252K
Sale	Common Stock	1,678	$175.07	$294K
Sale	Common Stock	1,517	$173.33	$263K

Holdings After Transaction: Common Stock — 80,506 shares (Direct)

Footnotes (1)

1. F1. Shares sold to satisfy tax withholding obligations upon the vesting of Restricted Stock Units and to cover related broker fees.

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Form 4 Insider Transactions: What Each Field Means →

Accepted by SEC EDGAR 01/08/2026 - 05:21 PM Learn about SEC filing dates

FAQ

What insider transaction did Insmed (INSM) report in this Form 4?

The filing shows that Chief Financial Officer Sara Bonstein sold small amounts of Insmed Inc. common stock on three dates in January 2026.

How many Insmed (INSM) shares did the CFO sell and at what prices?

Sara Bonstein sold 1,517 shares at $173.33 on January 6, 1,678 shares at $175.07 on January 7, and 1,447 shares at $174.17 on January 8, 2026.

Why did Insmed27s CFO sell these shares?

The filing explains that the shares were sold to satisfy tax withholding obligations upon the vesting of Restricted Stock Units and to cover related broker fees.

How many Insmed (INSM) shares does the CFO own after these sales?

After the reported transactions, Sara Bonstein directly owned 80,506 shares of Insmed Inc. common stock.

Are the reported Insmed (INSM) transactions direct or indirect holdings?

The Form 4 shows the holdings as direct ownership, with no nature of indirect beneficial ownership indicated.

Did this Insmed (INSM) Form 4 include any derivative securities?

No derivative securities are reported as acquired or disposed of in the tables; only common stock sales are listed.

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).

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^*

Bonstein Sara

(Last) (First) (Middle)

700 US HIGHWAY 202/206

(Street)

BRIDGEWATER NJ 08807

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
INSMED Inc [ INSM ]

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

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Financial Officer

3. Date of Earliest Transaction (Month/Day/Year)
01/06/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

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
Common Stock	01/06/2026		S(1)		1,517	D	$173.33	83,631	D
Common Stock	01/07/2026		S(1)		1,678	D	$175.07	81,953	D
Common Stock	01/08/2026		S(1)		1,447	D	$174.17	80,506	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. Shares sold to satisfy tax withholding obligations upon the vesting of Restricted Stock Units and to cover related broker fees.

Remarks:

	/s/ Sara Bonstein, by Michael A. Smith as Attorney-in-fact	01/08/2026
	** 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.