Amendment to Schedule 13D for Custom Truck One Source, Inc.

This Amendment No. 1 to Schedule 13D, filed by Capitol Acquisition Management IV LLC and related parties, updates the ownership details of Custom Truck One Source, Inc.'s common stock. The amendment reports a distribution in-kind of 3,670,279 shares of Common Stock to members of Management IV on October 17, 2025, with Mr. Ein acquiring 3,553,612 shares. As of July 28, 2025, Mr. Ein is the record holder of 5,139,319 shares and options to purchase 20,000 shares. The Reporting Persons have ceased to be beneficial owners of more than five percent of the outstanding Common Stock. The filing includes signatures from Mark Ein and Dyson Dryden, representing the reporting entities.