X0508 4 2025-11-03 0 0001003078 MSC INDUSTRIAL DIRECT CO INC MSM 0001947693 McIsaac Martina C/O MSC INDUSTRIAL DIRECT CO., INC. 515 BROADHOLLOW ROAD MELVILLE NY 11747 0 1 0 0 President & COO 0 Class A Common Stock, $0.001 par value 2025-11-03 4 M 0 959 0 A 6386 D Class A Common Stock, $0.001 par value 2025-11-03 4 M 0 76.614 0 A 6463 D Class A Common Stock, $0.001 par value 2025-11-03 4 F 0 252.614 84.79 D 6210 D Restricted Stock Units (RSU) 2025-11-03 4 A 0 20049 0 A Class A Common Stock, $0.001 par value 20049 20049 D Restricted Stock Units (RSU) 2025-11-03 4 M 0 959 0 D Class A Common Stock, $0.001 par value 959 1918 D Dividend Equivalent Units 2025-11-03 4 M 0 76.614 0 D Class A Common Stock, $0.001 par value 76.614 798 D Each RSU represents a contingent right to receive one share of Common Stock. The dividend equivalent units accrued with respect to outstanding awards of restricted stock units (RSUs) and vest at the same time(s) as the underlying RSUs. Each dividend equivalent unit represents a contingent right to receive one share of Common Stock. Disposition of Class A Common Stock to the Issuer to cover tax withholding obligations arising from the vesting of RSUs and DEUs. 20,049 RSUs were granted on November 3, 2025. 5,012 RSUs vest on each of November 3, 2026, November 3, 2027, and November 3, 2028, and 5,013 RSUs vest on November 3, 2029, provided that the Reporting Person remains continuously employed by the Issuer through each applicable vesting date. The vested shares will be delivered to the Reporting Person upon vesting. 3,835 RSUs were granted on November 3, 2023. 958 RSUs vested on November 3, 2024 and 959 RSUs vested on November 3, 2025. 959 RSUs vest on each of November 3, 2026 and November 3, 2027, provided that the Reporting Person remains continuously employed by the Issuer through each applicable vesting date. The vested shares will be delivered to the Reporting Person upon vesting. /s/ Martina McIsaac 2025-11-05