Company: SBXD
Filing Date: 2025-09-04
Form Type: 425
Source: 0001104659-25-087514
Chunk: 1

Company: SilverBox Corp IV
Filing Date: 2025-09-04
Form: 425
Chunk 1
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 shares included as part of the units                                                                                           |     | SBXD      |     | New York Stock Exchange LLC |
| Redeemable 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 (17 CFR § 230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR § 240.12b-2).

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 8.01. | Other Events. |

On
September 3, 2025, Parataxis Holdings Inc., a Delaware corporation (“Pubco”), and Parataxis Holdings LLC, a Delaware limited
liability company and an affiliate of Parataxis Capital Management LLC (“Parataxis”), filed a Registration Statement on Form
S-4 (File No. 333-289994) (as amended and supplemented from time to time, the “Registration Statement”) relating to the previously
announced proposed business combination (the “Business Combination”) between SilverBox Corp IV (“SilverBox,” together
with Parataxis and Pubco, the “Parties”) and Parataxis. The Registration Statement contains a preliminary proxy statement of SilverBox and a prospectus of Pubco in connection with the Business Combination. While the Registration Statement has not yet become effective and the information contained therein is subject to change, it provides important information about SilverBox, Parataxis, Pubco and the Business Combination.

IMPORTANT INFORMATION

General

This communication is being made in respect of the proposed business combination (the “Business Combination”) among SilverBox Corp IV (“SilverBox”), Parataxis Holdings LLC (“Parataxis”) and Parataxis Holdings Inc. (“Pubco,” and together with SilverBox and Parataxis, the “Parties”). The information contained herein does not purport to be all-inclusive and none of SilverBox, Parataxis or their respective affiliates makes any representation or warranty, express or implied, as to the accuracy, completeness or reliability