Proposed Common stock sale by INSM (NASDAQ: INSM) with insider William Lewis activity

Rhea-AI Filing Summary

INSM filed a Form 144 reporting proposed sales of Common stock and recent stock-plan related activity. The cover lists a proposed sale date of 04/06/2026 on NASDAQ and identifies William Lewis as the reporting seller. The filing itemizes multiple reported sales by William Lewis dated between 01/06/2026 and 03/19/2026, each with the disclosed reported share counts.

Insights

Securities Counsel

Form 144 documents proposed resale activity and recent plan-related transactions by an insider.

Form 144 is a notice of proposed sale under resale rules; it lists a proposed sale date of 04/06/2026 and recent sales by William Lewis on specific dates. The entries are transactional records, not company operational disclosures.

Cash‑flow treatment and underwriting or distribution details are not provided in the excerpt; subsequent filings or broker confirmations would show execution results.

Key Figures

Proposed sale date: 04/06/2026 Reported sale - 03/19/2026: 10,699 Reported sale - 03/05/2026: 10,699 +4 more

7 metrics

Proposed sale date 04/06/2026 Proposed sale listed on the cover

Reported sale - 03/19/2026 10,699 Shares shown under "Securities Sold During The Past 3 Months" on 03/19/2026

Reported sale - 03/05/2026 10,699 Shares shown under "Securities Sold During The Past 3 Months" on 03/05/2026

Reported sale - 02/19/2026 10,699 Shares shown under "Securities Sold During The Past 3 Months" on 02/19/2026

Reported sale - 02/09/2026 13,396 Shares shown under "Securities Sold During The Past 3 Months" on 02/09/2026

Reported sale - 01/12/2026 19,215 Shares shown under "Securities Sold During The Past 3 Months" on 01/12/2026

Exchange NASDAQ Securities listed as trading on NASDAQ in the cover information

Key Terms

Form 144, Stock Plan Activity, Securities Sold During The Past 3 Months

3 terms

Form 144 regulatory

"144: Securities To Be Sold"

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 | 04/06/2026 | Stock Plan Activity"

Securities Sold During The Past 3 Months regulatory

"144: Securities Sold During The Past 3 Months"

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

144: Issuer Information

Name of Issuer

SEC File Number

Address of Issuer

Phone

Name of Person for Whose Account the Securities are To Be Sold

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

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	1746319	215551896	04/06/2026	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	04/06/2026	Stock Plan Activity	Issuer			10699	04/06/2026	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	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
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	01/12/2026	19215	3247325
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	01/08/2026	3223	561349
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	01/07/2026	2357	412639
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	01/06/2026	4096	709959

144: Remarks and Signature

Remarks

Date of Notice

Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1

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

ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)

FAQ

What does INSM's Form 144 on 04/06/2026 report?

It reports a proposed sale of Common stock dated 04/06/2026. The filing also lists multiple recent sales by William Lewis between 01/06/2026 and 03/19/2026, with reported share quantities for each entry.

Who is the reporting seller in the INSM Form 144?

The filing identifies William Lewis as the reporting seller. The document shows William Lewis's address and multiple dated sales entries that fall under "Securities Sold During The Past 3 Months."

Which dates show reported sales in the Form 144 excerpt for INSM?

Reported sale dates include 01/06/2026, 01/07/2026, 01/08/2026, 01/12/2026, 01/20/2026, 02/03/2026, 02/09/2026, 02/19/2026, 03/05/2026, and 03/19/2026. Each date is paired with a reported quantity in the excerpt.

Does the excerpt state how many shares were proposed for sale on 04/06/2026?

The cover shows the proposed sale date 04/06/2026 but does not attach a single aggregated number to that proposed sale in the excerpt. The excerpt instead lists individual reported sale quantities on prior dates.

Was the Form 144 tied to stock plan activity?

The excerpt includes the phrase "Stock Plan Activity" alongside the 04/06/2026 entry. That indicates some transactions noted relate to stock plan movements, as presented in the filing excerpt.