Company: SBXD
Filing Date: 2025-08-07
Form Type: 425
Source: 0001104659-25-074863
Chunk: 1

Company: SilverBox Corp IV
Filing Date: 2025-08-07
Form: 425
Chunk 1
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emable Warrants included as part of the units, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50 |     | SBXD.WS   |     | New York Stock Exchange LLC |

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company x

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Item 1.01 Entry into a Material Definitive Agreement.

Business Combination Agreement

On August 6, 2025 (the “Execution Date”), SilverBox Corp IV, a Cayman Islands exempted company (“SPAC”), Parataxis Holdings Inc., a Delaware
corporation (“Pubco”), PTX Merger Sub I Inc., a Delaware corporation and a wholly-owned subsidiary of Pubco (“SPAC Merger Sub”), PTX Merger Sub II LLC, a Delaware limited liability company and a wholly-owned subsidiary of Pubco (“Company Merger Sub”), Parataxis Holdings LLC, a Delaware limited liability company (the “Company”), SilverBox Sponsor
IV LLC, a Delaware limited liability company (the “Sponsor”), solely for certain limited purposes as representative
of the SPAC Shareholders (the “SPAC Representative”), and Edward Chin, solely for certain limited purposes as representative
of the Company Holders (the “Seller Representative”), entered into a business combination agreement (the “Business Combination Agreement” and, the transactions contemplated by the Business Combination Agreement, the “Business Combination”).
Capitalized terms used in this Current Report on Form 8-K but not otherwise defined herein have the meanings given to them in the Business
Combination Agreement.

Pursuant to the Business Combination
Agreement, and subject to the terms and conditions set forth therein, (a) SPAC Merger Sub will merge with and into SPAC, with SPAC continuing
as the surviving company (the “SPAC Merger”), and with each SPAC Shareholder receiving one share of Pubco Class A common
stock (“Pubco Class A Stock”) for each SPAC Class A Ordinary