INSM insider files Form 144 to sell shares

INSM reported a Form 144 notice reporting proposed sales of Common Stock by William Lewis.

Rhea-AI Filing Summary

INSM reported a Form 144 notice reporting proposed sales of Common Stock by William Lewis. The filing lists multiple proposed sale dates and quantities, including 7,605 shares on 06/03/2026 and 25,564 shares on 05/18/2026. The entries show share counts tied to each sale row and resulting share figures on the same lines.

Insights

Insider Transactions Analyst

Routine Form 144 notice showing staged proposed dispositions by a reporting holder.

The excerpt lists multiple proposed sale dates and share amounts attributed to William Lewis, presented as stock plan activity and separate sale rows. The filing is a notice of intended resale rather than a statement that sales have settled.

Cash‑flow treatment and method of sale are not specified in the excerpt; subsequent filings or broker reports would confirm execution details.

Key Figures

Proposed sale: 7,605 shares Proposed sale: 25,564 shares Proposed sale: 13,283 shares +2 more

5 metrics

Proposed sale 7,605 shares 06/03/2026 row

Proposed sale 25,564 shares 05/18/2026 row

Proposed sale 13,283 shares 05/13/2026 row

Proposed sale 10,699 shares multiple rows (05/04, 04/16, 04/06, 03/19/2026)

Per-row associated figure 777,746 shares 06/03/2026 row (listed alongside 7,605)

Key Terms

Form 144, Stock Plan Activity, Issuer

3 terms

Form 144 regulatory

"Filer Information | 144: Filer Information"

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.

Stock Plan Activity financial

"Common | 06/01/2026 | Stock Plan Activity"

Issuer regulatory

"Stock Plan Activity | Issuer"

FAQ

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

What did INSM's Form 144 disclose about William Lewis's sales?

The Form 144 lists proposed sales of Common Stock by William Lewis on multiple dates. It includes entries such as 7,605 shares on 06/03/2026 and 25,564 shares on 05/18/2026, each shown with an associated share figure on the same line.

Does the Form 144 mean William Lewis already sold the shares?

No, the Form 144 is a notice of proposed resale under Rule 144 rather than confirmation of completed trades. The filing lists intended sale dates and quantities; execution and settlement are not confirmed within the provided excerpt.

How many shares were listed for sale on 05/13/2026 in the INSM filing?

The filing shows 13,283 shares tied to the date 05/13/2026 in William Lewis's row. That number appears in the sale row and is reported alongside the per‑row share figure also shown on that line.

Does the Form 144 show post‑transaction holdings for William Lewis?

Each sale row contains a second numeric figure on the same line that appears to reflect a share count associated with that entry (for example, 777,746 on the 06/03/2026 row). The excerpt does not label those figures beyond their placement in the rows.

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

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Accepted by SEC EDGAR 06/08/2026 - 04:34 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	0001402051
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	9089779900
Name of Person for Whose Account the Securities are To Be Sold	William Lewis
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 Washington DC 20006	6515	612576	216752451	06/08/2026	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			6515	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
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	06/03/2026	7605	777746
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/18/2026	25564	2718106
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/13/2026	13283	1543186
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/04/2026	10699	1469434
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	04/16/2026	10699	1540292
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	04/06/2026	10699	1746319
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	03/19/2026	10699	1535514

144: Remarks and Signature

Remarks
Date of Notice	06/08/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	09/04/2025
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	William Lewis
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)