Sec Form 3 Filing - Versaggi Shannon @ SiteOne Landscape Supply, Inc. - 2023-05-11

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 Versaggi Shannon 2. Issuer Name and Ticker or Trading Symbol SiteOne Landscape Supply, Inc. [ SITE] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) SVP Marketing (Last) (First) (Middle) MANSELL OVERLOOK, 300 COLONIAL CENTER PARKWAY, SUITE 600 3. Date of Earliest Transaction (MM/DD/YY) 05/11/2023 (Street) ROSWELL, GA30076 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 Common Stock 2,110 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 Share Units ( 6 ) ( 1 ) ( 1 ) Common Stock 591 D Restricted Share Units ( 6 ) ( 2 ) ( 2 ) Common Stock 236 D Restricted Share Units ( 6 ) ( 3 ) ( 3 ) Common Stock 451 D Restricted Share Units ( 6 ) ( 4 ) ( 4 ) Common Stock 697 D Restricted Share Units ( 6 ) ( 5 ) ( 5 ) Common Stock 1,339 D Stock Options (Right to Buy) ( 7 ) ( 7 ) ( 7 ) Common Stock 5,903 D Stock Options (Right to Buy) ( 8 ) ( 8 ) ( 8 ) Common Stock 7,094 D Stock Options (Right to Buy) ( 9 ) ( 9 ) ( 9 ) Common Stock 3,114 D Stock Options (Right to Buy) ( 10 ) ( 10 ) ( 10 ) Common Stock 2,963 D Stock Options (Right to Buy) ( 11 ) ( 11 ) ( 11 ) Common Stock 2,811 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Versaggi Shannon MANSELL OVERLOOK 300 COLONIAL CENTER PARKWAY, SUITE 600 ROSWELL, GA30076 SVP Marketing Signatures /s/ Briley Brisendine, Attorney-in-fact for Shannon Versaggi 05/15/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On February 17, 2020, the Reporting Person was granted 2,364 restricted stock units ("RSUs"), vesting in four equal annual installments beginning on February 17, 2021, subject to the Reporting Person's continued employment. Prior to the filing of this Form 3, 1,773 of these RSUs had vested. ( 2 )On February 17, 2020, the Reporting Person was granted 945 RSUs, vesting in four equal annual installments beginning on February 17, 2021, subject to the Reporting Person's continued employment. Prior to the filing of this Form 3, 709 of these RSUs had vested. ( 3 )On February 11, 2021, the Reporting Person was granted 902 RSUs, vesting in four equal annual installments beginning on February 11, 2022, subject to the Reporting Person's continued employment. Prior to the filing of this Form 3, 451 of these RSUs had vested. ( 4 )On February 10, 2022, the Reporting Person was granted 929 RSUs, vesting in four equal annual installments beginning on February 10, 2023, subject to the Reporting Person's continued employment. Prior to the filing of this Form 3, 232 of these RSUs had vested. ( 5 )On February 9, 2023, the Reporting Person was granted 1,339 RSUs, vesting in four equal annual installments beginning on February 9, 2024, subject to the Reporting Person's continued employment. Prior to the filing of this Form 3, none of these RSUs had vested. ( 6 )RSUs convert into shares of Common Stock upon vesting on a one-for-one basis. ( 7 )5,903 options were granted on February 17, 2020, and vest and become exercisable ratably in four installments on each anniversary of February 17, 2020, subject to the Reporting Person's continued employment. Prior to the filing of this Form 3, 4,427 of these options that remain outstanding had vested. ( 8 )7,094 options were granted on February 17, 2020, and vest and become exercisable ratably in four installments on each anniversary of February 17, 2020, subject to the Reporting Person's continued employment. Prior to the filing of this Form 3, 5,321 of these options that remain outstanding had vested. ( 9 )3,114 options were granted on February 11, 2021, and vest and become exercisable ratably in four installments on each anniversary of February 11, 2021, subject to the Reporting Person's continued employment. Prior to the filing of this Form 3, 1,557 of these options that remain outstanding had vested. ( 10 )2,963 options were granted on February 10, 2022, and vest and become exercisable ratably in four installments on each anniversary of February 10, 2022, subject to the Reporting Person's continued employment. Prior to the filing of this Form 3, 741 of these options that remain outstanding had vested. ( 11 )2,811 options were granted on February 9, 2023, and vest and become exercisable ratably in four installments on each anniversary of February 9, 2023, subject to the Reporting Person's continued employment. Prior to the filing of this Form 3, none of these options that remain outstanding had vested.

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

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