Company: SLDE
Filing Date: 2025-06-17
Form Type: S-1MEF
Source: 0001193125-25-142181
Chunk: 1

Company: Slide Insurance Holdings, Inc.
Filing Date: 2025-06-17
Form: S-1MEF
Chunk 1
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 the earlier effective registration statement for the same offering. ☒ 333-287556 If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐ If this form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐ Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-acceleratedfiler, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2of the Exchange Act.

| Large accelerated filer |     | ☐ |     | Accelerated filer         |     | ☐ |
| Non-accelerated filer   |     | ☒ |     | Smaller reporting company |     | ☐ |
|                         |     |   |     | Emerging growth company   |     | ☒ |

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 7(a)(2)(B) of the Securities Act. ☐ The Registration Statement shall become effective upon filing in accordance with Rule 462(b) promulgated under the Securities Act of 1933, as amended.

EXPLANATORY NOTE

This Registration Statement is being filed pursuant to Rule 462(b) under the Securities Act of 1933, as amended (the
“Securities Act”), for the sole purpose of increasing the aggregate number of shares of common stock offered by Slide Insurance Holdings, Inc. (the “Registrant”) by 4,600,000 shares, 600,000 of which are subject to purchase
upon exercise of the underwriters’ option to purchase additional shares of the Registrant’s common stock. The additional securities that are being registered for sale are in an amount and at a price that together represent not more than
20% of the maximum aggregate offering price set forth in the filing fee table filed as an exhibit to the Initial Registration Statement (defined below). The contents of the Registration Statement on Form S-1,