144 0001785100 XXXXXXXX LIVE 0001709682 Custom Truck One Source, Inc. 001-38186 7701 INDEPENDENCE AVENUE KANSAS CITY MO 64125 (816) 241-4888 BARRETT RAYMOND TODD Former Officer Common Stock Morgan Stanley Smith Barney LLC

1 New York Plaza 8th Floor New York IN 10004

13333 93968.00 226625924 04/09/2026 NYSE Common Stock 04/09/2026 Exercise of employee stock options Custom Truck One Source, Inc. N 13333 04/09/2026 Broker assisted cashless exercise Y 04/10/2026 Raymond Todd Barrett