Sec Form 4 Filing - Carroll Austen @ SEACOAST BANKING CORP OF FLORIDA - 2024-02-29

FORM 4 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 Carroll Austen 2. Issuer Name and Ticker or Trading Symbol SEACOAST BANKING CORP OF FLORIDA [ SBCF] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) EVP, Chief Lending Officer (Last) (First) (Middle) P.O. BOX 9012 3. Date of Earliest Transaction (MM/DD/YY) 02/29/2024 (Street) STUART, FL34995 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 02/29/2024 A( 1 ) 5,242 A $ 0 ( 1 ) 16,870 D Common Stock 5,290 D ( 2 ) Common Stock 2,439 D ( 3 ) Common Stock 582 D ( 4 )

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 Deriva tive 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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Carroll Austen P.O. BOX 9012 STUART, FL34995 EVP, Chief Lending Officer Signatures /s/ Kathy L. Hsu as Power of Attorney for Austen Carroll 03/04/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents shares subject to performance based restricted stock units ("PSUs") granted on April 1, 2021, that were subject to performance requirements which were attained over a period ending December 23, 2023. On February 29, 2024, the Company's Compensation and Governance Committee certified the number of shares attained based on the performance criteria, which will vest on December 31, 2024, provided the recipient remains in continuous service with the Company on the vesting date. ( 2 )Represents an unvested time-based restricted stock award granted on April 1 2023, which shall vest over 3 years in one-third increments, beginning April 1, 2024, and on each anniversary thereafter, subject to continued employment. ( 3 )Represents an unvested time-based restricted stock grant on April 1, 2022, which shall vest over 3 years in on-third increments, beginning April 1, 2023, and on each anniversary thereafter, subject to continued employment. ( 4 )Represents an unvested time-based restricted stock award granted on April 1, 2021, which shall vest over 3 years in one-third increments, beginning April 1, 2022, and on each anniversary thereafter, subject to continued employment.

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).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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