Insmed former officer lists $1.12M in shares for sale

The remarks tie the stock-plan shares to tax withholding upon restricted-stock-unit vesting and related broker fees.

Available on EDGAR 11/03/2026 - 04:34 PM EST Accepted by SEC EDGAR 11/03/2026 - 04:34 PM EST Learn about SEC filing dates

Rhea-AI Filing Summary

Sara Bonstein, a former officer of INSMED Inc. (INSM), reported 10,261 common shares for sale through Merrill Lynch, with an approximate sale date of November 3, 2026. The securities information lists an aggregate market value of $1,121,629. Her remarks state that shares were sold to satisfy tax withholding upon vesting of Restricted Stock Units and to cover related broker fees.

Key Figures

Common shares reported for sale: 10,261 shares Aggregate market value: $1,121,629 Shares outstanding: 219,380,309 shares

3 metrics

Common shares reported for sale 10,261 shares Approximate sale date: November 3, 2026

Aggregate market value $1,121,629 Common shares reported for sale

Shares outstanding 219,380,309 shares Number listed in the securities information

Key Terms

Rule 144, Restricted Stock Units, tax withholding obligations

3 terms

Rule 144 regulatory

"See the definition of "person" in paragraph (a) of Rule 144"

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Restricted Stock Units financial

"upon the vesting of Restricted Stock Units"

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

"to satisfy tax withholding obligations"

FAQ

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

How many INSM shares did Sara Bonstein report for sale?

Sara Bonstein reported 10,261 common shares for sale, with an aggregate market value of $1,121,629 and an approximate sale date of November 3, 2026.

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

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Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001604019
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	INSMED INC
SEC File Number
Address of Issuer	700 US Highway 202/206 Bridgewater NEW JERSEY 08807
Phone	9089779900
Name of Person for Whose Account the Securities are To Be Sold	Sara Bonstein
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Former Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Merrill Lynch 1800 K ST NW Suite 800 Washington DC 20006	10261	1121629	219380309	11/03/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	10/30/2026	Stock Plan Activity	Issuer			10261	10/30/2026	n/a

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Nothing to Report

144: Remarks and Signature

Remarks	Shares were sold to satisfy tax withholding obligations upon the vesting of Restricted Stock Units and to cover related broker fees
Date of Notice	11/03/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	Sara Bonstein
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)