SEC FORM 4

SEC FORM 4SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

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

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Nelson Daniel D

(Last)

(First)

(Middle)

1540 BROADWAY, STE 1010

(Street)

NEW YORK

10036

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
BlockchAIn Digital Infrastructure, Inc. [ AIB ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
	Officer (give title below)	Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/16/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	03/16/2026		A		37,527	A	⁽¹⁾	37,527	D
Common Stock	03/16/2026		A		2,917	A	⁽¹⁾	2,917	I	By The Nelson Revocable Living Trust⁽²⁾

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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option (right to buy)	$1,594.17	03/16/2026		A		59		03/16/2026	09/28/2032	Common Stock	59	⁽³⁾	59	D
Stock Option (right to buy)	$1,594.17	03/16/2026		A		10		03/16/2026	09/28/2032	Common Stock	10	⁽⁴⁾	10	D
Stock Option (right to buy)	$1,157.06	03/16/2026		A		195		03/16/2026	11/21/2033	Common Stock	195	⁽⁵⁾	195	D

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 ("SGN"), 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 reporting person received 0.09334 common shares of BlockchAIn for every share of common stock of SGN held by the reporting person, subject to rounding adjustments. The last reported sale price of SGN common stock after the Closing was $0.54 per share, as reported on March 16, 2026. The first reported sale price after the Closing of BlockchAIn's common stock was $4.60 per share, as reported on March 17, 2026.

2. The reporting person is a co-trustee of The Nelson Revocable Living Trust, an Arizona trust provided for by the Nelson Revocable Living Trust Agreement established on March 9, 1999 and amended and restated on November 21, 2005. The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.

3. Pursuant to the terms of the Business Combination Agreement, on the date of the Closing, the reporting person's employee stock option to acquire 625 shares of SGN common stock for $148.80 per share was assumed by BlockchAIn and automatically converted into an option to purchase 59 common shares of BlockchAIn exercisable for $1,594.17 per share.

4. Pursuant to the terms of the Business Combination Agreement, on the date of the Closing, the reporting person's employee stock option to acquire 105 shares of SGN common stock for $148.80 per share was assumed by BlockchAIn and automatically converted into an option to purchase 10 common shares of BlockchAIn exercisable for $1,594.17 per share.

5. Pursuant to the terms of the Business Combination Agreement, on the date of the Closing, the reporting person's employee stock option to acquire 2,084 shares of SGN common stock for $108.00 per share was assumed by BlockchAIn and automatically converted into an option to purchase 195 common shares of BlockchAIn exercisable for $1,157.06 per share.

	/s/ Daniel D. Nelson	03/18/2026
	** Signature of Reporting Person	Date
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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

SEC Form 4 filed by Nelson Daniel D