Insmed (NASDAQ: INSM) CFO sells 2,404 shares to cover RSU taxes

Rhea-AI Filing Summary

Insmed Inc.’s Chief Financial Officer Sara Bonstein reported an automatic sale of shares tied to equity compensation. On the reported date, 2,404 shares of common stock were sold at $102.27 per share. According to the footnote, the shares were sold to satisfy tax withholding obligations when Restricted Stock Units vested and to cover related broker fees, rather than as a discretionary portfolio move. After this transaction, Bonstein directly owned 69,082 Insmed shares, so the filing mainly reflects routine tax handling on stock-based compensation.

Insider Trade Summary

Net Seller: 2,404 shares ($245,857)

Net Sell 1 txn

Insider Bonstein Sara

Role Chief Financial Officer

Sold 2,404 shs ($246K)

Type	Security	Shares	Price	Value
Sale	Common Stock	2,404	$102.27	$246K

Holdings After Transaction: Common Stock — 69,082 shares (Direct, null)

Footnotes (1)

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Key Figures

Shares sold: 2,404 shares Sale price: $102.27 per share Shares owned after: 69,082 shares

3 metrics

Shares sold 2,404 shares Common stock sold in tax-related transaction

Sale price $102.27 per share Price for common stock sale

Shares owned after 69,082 shares Direct holdings after transaction

Key Terms

Restricted Stock Units, tax withholding obligations, open-market sale

3 terms

Restricted Stock Units financial

"upon the vesting of Restricted Stock Units and to cover related broker fees"

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 sold to satisfy tax withholding obligations upon the vesting of Restricted Stock Units"

open-market sale financial

"transaction_action: open-market sale"

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

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Form 4 Insider Transactions: What Each Field Means →

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 NEW JERSEY 08807

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/03/2026

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
Common Stock	06/03/2026		S(1)		2,404	D	$102.27	69,082	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	06/05/2026
	** 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)

FAQ

What insider transaction did Insmed (INSM) disclose for CFO Sara Bonstein?

Insmed disclosed that CFO Sara Bonstein reported a sale of 2,404 shares of common stock. The filing notes the shares were sold to cover tax withholding obligations and related broker fees upon vesting of Restricted Stock Units, leaving her with 69,082 shares directly owned.

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

The CFO reported selling 2,404 Insmed common shares at a price of $102.27 per share. The footnote clarifies the sale was made to satisfy tax withholding obligations linked to Restricted Stock Unit vesting and to pay associated broker fees, not as a discretionary open-market reduction.

How many Insmed (INSM) shares does the CFO hold after this Form 4 transaction?

After the reported transaction, CFO Sara Bonstein directly owned 69,082 Insmed common shares. This post-transaction holding figure is disclosed in the Form 4 and shows her remaining equity stake following the tax-related sale of 2,404 shares tied to Restricted Stock Unit vesting.

Was the Insmed (INSM) CFO’s share sale part of routine tax withholding?

Yes. The Form 4 footnote states the 2,404 shares were sold to satisfy tax withholding obligations upon vesting of Restricted Stock Units and to cover broker fees. This indicates a routine, compensation-related sale rather than a discretionary trade based on market views or portfolio repositioning.

What type of security was involved in the Insmed (INSM) CFO Form 4 filing?

The Form 4 involves Insmed common stock linked to Restricted Stock Units. When the RSUs vested, 2,404 underlying common shares were sold to cover tax withholding and broker fees, as explained in the footnote, with the remaining vested shares contributing to the CFO’s 69,082-share direct ownership.