Sec Form 3 Filing - TWORECKE FRANK @ Greenbrook TMS Inc. - 2024-01-01

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 TWORECKE FRANK 2. Issuer Name and Ticker or Trading Symbol Greenbrook TMS Inc. [ GBNH] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O GREENBROOK TMS. 890 YONGE STREET, 7TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 01/01/2024 (Street) TORONTO, A6M4W3P4 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 Shares 40,000 I See Footnote ( 1 )

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 Options $ 10 ( 2 ) 10/03/2028 Common Shares 5,000 D Options $ 10.13 ( 4 ) ( 3 ) 02/03/2030 Common Shares 5,000 D Deferred Share Units $ 0 ( 5 ) ( 5 ) ( 6 ) Common Shares 251,018 ( 7 ) D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other TWORECKE FRANK C/O GREENBROOK TMS. 890 YONGE STREET 7TH FLOOR TORONTO, A6M4W3P4 X Signatures /s/William Leonard, Attorney-in-Fact 01/02/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The common shares are directly held by Tworecke Investments LLC, which is a limited liability company wholly owned by the Reporting Person. ( 2 )These options were granted pursuant to the Company's Amended Employee Stock Option Plan (the "Stock Option Plan"), as described in the Company's 2022 Meeting Information Circular, filed with the Securities and Exchange Commission on May 23, 2023. The options were granted on October 3, 2018 and fully vested on March 31, 2019 and accordingly, are all exercisable. ( 3 )These options were granted pursuant to the Stock Option Plan on February 3, 2020 and vested over a three year period, with one-third vesting on each of the 3 anniversaries of the date of the grant. As of the date hereof, all options are vested and exercisable. ( 4 )Converted to USD based on the average daily exchange rate of the Bank of Canada reported on December 29, 2023. Each option may be exercised for a price of $13.40 Canadian dollars. ( 5 )These deferred share units ("DSUs") were granted between June 15, 2021 and December 15, 2023 pursuant to the DSU Plan for non-employee directors, as described in the Company's 2022 Meeting Information Circular, filed with the Securities and Exchange Commission on May 23, 2023. The DSUs immediately vest upon grant, but holders thereof are not entitled to receive a payment in respect of the value of their DSUs until their tenure on the board of directors ceases. ( 6 )The DSUs do not expire. ( 7 )Mr. Tworecke will receive a payment in cash at the fair market value of the common shares represented by his or her DSUs generally within ten days of his elected redemption date. Mr. Tworecke's elected redemption date will not be earlier than the date he ceases to hold all positions with the Company and will not be later than December 31 of the year following the year in which he ceases to hold all positions with the Company.

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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