INSM Form 144: William Lewis lists planned share sales

INSM reports proposed sales of Common stock on a Form 144, listing multiple sale dates and share counts attributable to William Lewis under stock plan activity.

Rhea-AI Filing Summary

INSM reports proposed sales of Common stock on a Form 144, listing multiple sale dates and share counts attributable to William Lewis under stock plan activity. The filing lists transactions dated 04/06/2026, 03/19/2026, 03/05/2026, and earlier 2026 dates with corresponding numeric entries.

Insights

Securities Compliance Analyst

Form 144 notification of proposed resale activity by an insider.

Form 144 is a regulatory notice that a holder intends to sell restricted or control securities under applicable resale rules. The excerpt lists multiple dated entries tied to William Lewis and labels the activity as "Stock Plan Activity" and "Issuer."

These entries are procedural disclosures required before resale under Rule 144; timing and actual execution depend on market transactions and compliance with resale conditions stated in applicable securities rules.

Key Figures

Filing date shown: 04/16/2026 Entry on 04/06/2026: 1746319 Entry on 03/19/2026: 1535514 +5 more

8 metrics

Filing date shown 04/16/2026 Form 144 header date

Entry on 04/06/2026 1746319 Numeric entry listed next to 04/06/2026

Entry on 03/19/2026 1535514 Numeric entry listed next to 03/19/2026

Entry on 03/05/2026 1562311 Numeric entry listed next to 03/05/2026

Entry on 02/19/2026 1615250 Numeric entry listed next to 02/19/2026

Entry on 02/09/2026 1979774 Numeric entry listed next to 02/09/2026

Entry on 02/03/2026 470412 Numeric entry listed next to 02/03/2026

Entry on 01/20/2026 1700420 Numeric entry listed next to 01/20/2026

Key Terms

Form 144, Stock Plan Activity, Common

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

"04/16/2026 | Stock Plan Activity | Issuer"

Common financial

"Securities Information Common | Merrill Lynch 1800 K ST NW"

FAQ

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

What does INSM's Form 144 filing mean?

It notifies the SEC of proposed resale activity by a holder. The filing lists multiple dated transactions and identifies William Lewis and "Stock Plan Activity" as the context for the common stock entries.

Who is the selling party listed on the INSM Form 144?

The filing repeatedly names William Lewis at a Bridgewater, NJ address, showing multiple dated entries tied to his common stock transactions during early 2026.

Which dates are shown on the INSM Form 144 excerpt?

The excerpt lists several dates including 04/16/2026, 04/06/2026, 03/19/2026, 03/05/2026, and others in early 2026 associated with the reported common stock entries.

Does the INSM excerpt state how many shares will be sold?

The filing includes numeric entries adjacent to each date (for example 1746319 on 04/06/2026 and 1535514 on 03/19/2026), which are shown in the excerpt alongside the dated transactions.

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

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Accepted by SEC EDGAR 04/16/2026 - 04:17 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 Suite 800 Washington DC 20006	10699	1540292	215551896	04/16/2026	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	04/16/2026	Stock Plan Activity	Issuer			10699	04/16/2026	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	04/06/2026	10699	1746319
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	03/19/2026	10699	1535514
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	03/05/2026	10699	1562311
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	02/19/2026	10699	1615250
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	02/09/2026	13396	1979774
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	02/03/2026	3009	470412
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	01/20/2026	10699	1700420

144: Remarks and Signature

Remarks
Date of Notice	04/16/2026
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)