March 12, 2026 - 144: Report of proposed sale of securities

144: Filer Information

Filer CIK

0001437827

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

Perimeter Solutions Inc

SEC File Number

001-41027

Address of Issuer

8000 Maryland Avenue, Suite 350
Clayton
MISSOURI
63105

Phone

3143967343

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

Cromwell Harbor Supporting Foundation

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

Foundation of 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	UBS Financial Services Inc 1000 Harbor Blvd 3rd Floor Weehawken NJ 07086	115000	2655350	149440060	03/12/2026	NYSE

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	12/19/2025	Gift	William Thorndike		11/08/2021	500000	11/08/2021	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 Thorndike 800 Boylston Street, Suite 2220 Boston MA 02199	Common	03/04/2026	125000	3025666
William Thorndike 800 Boylston Street, Suite 2220 Boston MA 02199	Common	03/05/2026	100000	2401098
William Thondike 800 Boylston Street, Suite 2220 Boston MA 02199	Common	03/06/2026	100000	2357725
William Thorndike 800 Boylston Street, Suite 2220 Boston MA 02199	Common	03/09/2026	125000	2914666
William Thorndike 800 Boylston Street, Suite 2220 Boston MA 02199	Common	03/10/2026	100000	2358277
William Thorndike 800 Boylston Street Ste 2220 Boston MA 02199	Common	03/11/2026	100000	2313282

144: Remarks and Signature

Remarks

William Thorndike is a Director of the issuing company. The seller is a foundation of which William Thorndike is also a Director.

Date of Notice

03/12/2026

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

/s/Mijo Suric, for UBS Financial Services Inc, as attorney-in-fact for Cromwell Harbor Supporting Foundation

Form: 144

FORM 144