Insmed director plans sale of 25,000 company shares

INSMED Inc (INSM) is the issuer for a notice by director David R. Brennan covering a proposed sale of up to 25,000 shares of common stock under Rule 144.

Rhea-AI Filing Summary

INSMED Inc (INSM) is the issuer for a notice by director David R. Brennan covering a proposed sale of up to 25,000 shares of common stock under Rule 144. The shares are held in an account at Wells Fargo Clearing Services for the Revocable Trust of David R. Brennan, for which he serves as trustee.

The shares relate to equity grants from the issuer dated May 22, 2024, May 15, 2025, and May 22, 2026, and are listed with an aggregate market value of 3,099,729.14 as of a proposed sale date of September 9, 2026 on Nasdaq. The notice is dated September 10, 2026 and is a required disclosure before the potential sale.

Key Figures

Shares covered by Rule 144 notice: 25,000 shares Aggregate market value of shares: 3,099,729.14 Equity grant shares (05/22/2024): 6,780 shares +3 more

6 metrics

Shares covered by Rule 144 notice 25,000 shares Proposed sale of common stock under Rule 144

Aggregate market value of shares 3,099,729.14 Value for 25,000 common shares associated with proposed sale

Equity grant shares (05/22/2024) 6,780 shares Common stock from equity grant by issuer on May 22, 2024

Equity grant shares (05/15/2025) 13,162 shares Common stock from equity grant by issuer on May 15, 2025

Equity grant shares (05/22/2026) 5,058 shares Common stock from equity grant by issuer on May 22, 2026

Date of notice September 10, 2026 Filing date of the Form 144 notice by David R. Brennan

Key Terms

Rule 144, Equity grant, Revocable Trust, Issuer, +1 more

5 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.

Equity grant financial

"common | 05/22/2024 | Equity grant | Issuer"

Revocable Trust financial

"shares were sold in account of Revocable Trust of David R Brennan"

A revocable trust is a legal arrangement where the person who creates it keeps control and can change or cancel the trust at any time, while naming who will manage and receive the assets later. Think of it like a flexible folder for your investments and property that can be relabeled or reworked as circumstances change; it matters to investors because it determines how ownership is recorded, how easily assets transfer on incapacity or death, and whether holdings bypass public probate proceedings.

Issuer regulatory

"Equity grant | Issuer"

Nasdaq market

"218381503 | 09/09/2026 | Nasdaq"

The Nasdaq is a stock exchange where many companies' shares are bought and sold, functioning much like a marketplace for investments. It matters to investors because it provides a platform to buy and sell ownership stakes in companies, helping them track the value of those companies and make informed decisions. As one of the largest and most technology-focused markets, it also reflects trends and developments in the business world.

FAQ

What does the Form 144 filing disclose for INSM (INSMED Inc)?

It discloses that director David R. Brennan filed a Rule 144 notice for a potential sale of 25,000 shares of INSMED common stock, held in an account for the Revocable Trust of David R. Brennan at Wells Fargo Clearing Services.

How many INSM shares are covered by David R. Brennan’s Form 144?

The notice covers a potential sale of 25,000 shares of INSMED common stock. These shares are tied to three equity grants from the issuer dated May 22, 2024, May 15, 2025, and May 22, 2026.

What is the reported market value of the INSM shares in this Form 144?

The filing lists an aggregate market value of 3,099,729.14 for the 25,000 shares of INSMED common stock associated with the proposed Rule 144 sale as of a proposed sale date of September 9, 2026.

Who actually holds the INSM shares referenced in this Form 144 filing?

The shares are held in the account of the Revocable Trust of David R. Brennan, with David R. Brennan serving as trustee. The securities are custodied at Wells Fargo Clearing Services in St. Louis, Missouri.

On which market are the INSM shares in this Form 144 intended to be sold?

The securities information section associates the 25,000 shares of common stock with a proposed sale on Nasdaq on September 9, 2026, consistent with standard Rule 144 sale disclosures.

What types of transactions created the INSM shares covered by this Form 144?

All of the common shares listed as securities to be sold arose from equity grants by the issuer, INSMED Inc, with grant dates of May 22, 2024, May 15, 2025, and May 22, 2026.

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

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Available on EDGAR 09/10/2026 - 10:23 AM Accepted by SEC EDGAR 09/10/2026 - 10:22 AM Learn about SEC filing dates

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	0001609305
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	000-30739
Address of Issuer	700 US HIGHWAY 202/206 BRIDGEWATER NEW JERSEY 08807
Phone	908-977-9900
Name of Person for Whose Account the Securities are To Be Sold	Brennan David R
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	Director

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	Wells Fargo Clearing Services 1 North Jefferson Avenue St. Louis MO 63103	25000	3099729.14	218381503	09/09/2026	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	05/22/2024	Equity grant	Issuer			6780	05/22/2024	N/A
common	05/15/2025	Equity grant	Issuer			13162	05/15/2025	N/A
common	05/22/2026	Equity grant	Issuer			5058	05/22/2026	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 in account of Revocable Trust of David R Brennan, David R Brennan as trustee.
Date of Notice	09/10/2026
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	David R Brennan
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)