Sec Form 4 Filing - Hecklinski Jeffry @ Signing Day Sports, Inc. - 2026-03-16

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 Hecklinski Jeffry 2. Issuer Name and Ticker or Trading Symbol Signing Day Sports, Inc. [ SGN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) President (Last) (First) (Middle) C/O SIGNING DAY SPORTS, INC., 8355 EAST HARTFORD RD., SUITE 100 3. Date of Earliest Transaction (MM/DD/YY) 03/16/2026 (Street) SCOTTSDALE, AZ85255 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 03/16/2026 D 9,262 D 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 Stock Option (right to buy) $ 148.8 03/16/2026 D 834 ( 2 ) 03/14/2033 Common Stock 834 ( 2 ) 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Hecklinski Jeffry C/O SIGNING DAY SPORTS, INC. 8355 EAST HARTFORD RD., SUITE 100 SCOTTSDALE, AZ85255 X President Signatures /s/ Jeffry Hecklinski 03/18/2026 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Pursuant to the Business Combination Agreement, dated as of May 27, 2025, by and among Signing Day Sports, Inc., a Delaware corporation (the "Registrant"), One Blockchain LLC, a Delaware limited liability company, BlockchAIn Digital Infrastructure, Inc., a Delaware corporation ("BlockchAIn"), BCDI Merger Sub I Inc., a Delaware corporation, and BCDI Merger Sub II LLC, a Delaware limited liability company, as amended (the "Business Combination Agreement"), on the date of the closing (the "Closing") of the transactions contemplated by the Business Combination Agreement, or March 16, 2026 (the "Closing Date"), the reporting person received 0.09334 common shares of BlockchAIn for every share of common stock of the Registrant held by the reporting person, subject to rounding adjustments, having a market value of $4.60 per share based on the first reported sale price of the common stock of BlockchAIn on the NYSE American LLC after the Closing, which was reported on March 17, 2026. ( 2 )Pursuant to the terms of the Business Combination Agreement, on the Closing Date, the reporting person's option, which provided for vesting as to 209 shares immediately upon the date of grant, as to 156 shares on the one-year anniversary of the date of grant, and as to an aggregate of 469 shares in approximately equal increments at the end of each of the following 36 calendar months, immediately became fully vested, was assumed by BlockchAIn, and was automatically converted into an option to purchase 78 common shares of BlockchAIn exercisable for $1,594.17 per share.

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