INSM insider files Form 144 to sell shares

INSM reported proposed sales of common stock by an insider via Form 144.

Rhea-AI Filing Summary

INSM reported proposed sales of common stock by an insider via Form 144. The filing lists three proposed dispositions by Martina Flammer on 05/11/2026, 05/13/2026, and 05/14/2026, with the reported share amounts shown for each date.

The entries show 12,949 shares on 05/11/2026, 7,854 shares on 05/13/2026, and 10,479 shares on 05/14/2026, alongside the related beneficial ownership figures provided on each row.

Insights

Securities Compliance Counsel

Form 144 reports proposed insider dispositions on specified dates; filings notify the market of intended sales.

The notice lists three proposed dispositions by Martina Flammer with exact share counts and accompanying beneficial‑ownership figures for each transaction date. Form 144 is a regulatory notice of intended sale, not proof that the sales executed.

Timing and execution details are not provided in the excerpt; subsequent public filings or trade records would confirm whether these proposed sales were completed.

Key Figures

Proposed sale: 12,949 shares Proposed sale: 7,854 shares Proposed sale: 10,479 shares +3 more

6 metrics

Proposed sale 12,949 shares Proposed disposition on 05/11/2026

Proposed sale 7,854 shares Proposed disposition on 05/13/2026

Proposed sale 10,479 shares Proposed disposition on 05/14/2026

Beneficial ownership 1,300,105 shares Beneficially owned as shown on 05/11/2026 row

Beneficial ownership 897,137 shares Beneficially owned as shown on 05/13/2026 row

Beneficial ownership 1,231,599 shares Beneficially owned as shown on 05/14/2026 row

Key Terms

Form 144, proposed disposition, beneficially owned

3 terms

Form 144 regulatory

"Form 144: Securities Sold During The Past 3 Months"

Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.

proposed disposition regulatory

"Securities To Be Sold — Stock Plan Activity — Issuer"

beneficially owned financial

"rows showing share counts alongside post‑transaction holdings"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

FAQ

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

What did INSM's Form 144 disclose about Martina Flammer's transactions?

Form 144 disclosed proposed dispositions by Martina Flammer on 05/11/2026, 05/13/2026, and 05/14/2026. The filing lists 12,949, 7,854, and 10,479 shares respectively, with accompanying beneficial‑ownership figures shown on each row.

Does the Form 144 confirm the shares were sold for INSM?

No; Form 144 notifies the SEC of an intended sale but does not confirm execution. Post‑sale confirmations would appear in trade records or subsequent filings reporting completed transactions.

What are the beneficial ownership figures shown with each sale for INSM?

Each sale row includes a beneficial‑ownership number: 1,300,105 on 05/11/2026, 897,137 on 05/13/2026, and 1,231,599 on 05/14/2026, as listed alongside the respective proposed dispositions.

What does filing Form 144 mean for compliance and reporting?

Filing Form 144 signals a reporting person intends to sell restricted or control securities and meets disclosure thresholds. It fulfills a notice requirement but does not itself effect a transfer or sale of the securities.

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

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Accepted by SEC EDGAR 06/03/2026 - 04:35 PM EDT 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	0001796960
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 INCORPORATED
SEC File Number	000-30739
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	Martina Flammer
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	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	2566	262424	216752451	06/03/2026	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	06/01/2026	Stock Plan Activity	Issuer			2566	06/01/2026	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

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Martina Flammer 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/14/2026	10479	1231599
Martina Flammer 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/13/2026	7854	897137
Martina Flammer 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/11/2026	12949	1300105

144: Remarks and Signature

Remarks
Date of Notice	06/03/2026
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	Martina Flammer
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)