Sec Form 3 Filing - Clark Gregory Haefele @ MSC INDUSTRIAL DIRECT CO INC - 2025-08-08

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Clark Gregory Haefele 2. Issuer Name and Ticker or Trading Symbol MSC INDUSTRIAL DIRECT CO INC [ MSM] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) VP & Interim CFO (Last) (First) (Middle) C/O MSC INDUSTRIAL DIRECT CO., INC., 515 BROADHOLLOW ROAD 3. Date of Earliest Transaction (MM/DD/YY) 08/08/2025 (Street) MELVILLE, NY11747 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Class A Common Stock, $0.001 par value 0 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Restricted Stock Units (RSU) ( 2 ) ( 1 ) ( 1 ) Class A Common Stock, $0.001 par value 221 D Restricted Stock Units (RSU) ( 2 ) ( 3 ) ( 3 ) Class A Common Stock, $0.001 par value 454 D Restricted Stock Units (RSU) ( 2 ) ( 4 ) ( 4 ) Class A Common Stock, $0.001 par value 576 D Restricted Stock Units (RSU) ( 2 ) ( 5 ) ( 5 ) Class A Common Stock, $0.001 par value 931 D Dividend Equivalent Units ( 6 ) ( 6 ) ( 6 ) Class A Common Stock, $0.001 par value 175 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Clark Gregory Haefele C/O MSC INDUSTRIAL DIRECT CO., INC. 515 BROADHOLLOW ROAD MELVILLE, NY11747 VP & Interim CFO Signatures /s/ Gregory Haefele Clark 08/15/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )882 RSUs were granted on November 5, 2021. 220 RSUs vested on each of November 5, 2022 and November 5, 2023 and 221 RSUs vested on November 5, 2024. 221 RSUs vest on November 5, 2025, 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. ( 2 )Each RSU represents a contingent right to receive one share of Common Stock. ( 3 )908 RSUs were granted on November 4, 2022. 227 RSUs vested on each of November 4, 2023 and November 4, 2024. 227 RSUs vest on each of November 4, 2025 and November 4, 2026, 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. ( 4 )767 RSUs were granted on November 3, 2023. 191 RSUs vested on November 3, 2024. 192 RSUs vest on each of November 3, 2025, 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. ( 5 )931 RSUs were granted on November 4, 2024. 232 RSUs vest on November 4, 2025, and 233 RSUs vest on each of November 4, 2026, November 4, 2027, and November 4, 2028, 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. ( 6 )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.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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