144 0001437827 XXXXXXXX LIVE 0001880319 Perimeter Solutions Inc 001-41027 8000 Maryland Avenue, Suite 350 Clayton MO 63105 3143967343 Cromwell Harbor Supporting Foundation Foundation of Director Common UBS Financial Services Inc

1000 Harbor Blvd 3rd Floor Weehawken NJ 07086

115000 2655350 149440060 03/12/2026 NYSE Common 12/19/2025 Gift William Thorndike Y 11/08/2021 500000 11/08/2021 N/A N 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 William Thorndike is a Director of the issuing company. The seller is a foundation of which William Thorndike is also a Director. 03/12/2026 /s/Mijo Suric, for UBS Financial Services Inc, as attorney-in-fact for Cromwell Harbor Supporting Foundation