Heinberg Marshall A 4

What Happened
Marshall A. Heinberg, a director of Custom Truck One Source, converted/exercised 48,346 restricted stock units (RSUs) on March 31, 2026 (transaction code M). The filing shows 48,346 shares were both acquired on conversion and disposed the same day (price reported $0.00 for the derivative transactions). On April 1, 2026 he was granted 34,605 RSUs (transaction code A) at $0.00; those RSUs are footnoted to vest on March 31, 2027 and have no expiration date. The filing does not report cash proceeds or a market sale price for the disposed shares.

Key Details

• Transaction dates and codes: 2026-03-31 (M — exercise/conversion of derivative, 48,346 shares acquired and 48,346 disposed, $0.00 reported); 2026-04-01 (A — grant/award, 34,605 RSUs, $0.00).
• Shares owned after the transactions: not reported in this Form 4.
• Footnotes: F1 — each RSU represents a contingent right to one share; F2 — the RSUs converted on Mar 31 vested in full on Mar 31, 2026; F3 — the 34,605 RSUs granted on Apr 1 will vest on Mar 31, 2027 and have no expiration.
• Filing date: Form 4 filed Apr 2, 2026 covering the Mar 31/Apr 1 transactions; the filing is not marked as late.

Context

• These were derivative/compensation-related moves (RSU conversion and grant), not an open-market buy or simple sale. The same-day “disposed” entry for the 48,346 converted shares is shown in the filing but no reason (e.g., sale proceeds or tax withholding) or sale price is provided, so the filing alone does not explain the disposition.
• RSU grants and vesting are routine executive/director compensation events and do not by themselves indicate the insider’s market view.