Neptune Insurance Holdings Inc.

We are incorporating by reference specified documents that we have filed with the SEC, which means that we

can disclose important information to you by referring you to those documents that are considered part of this

prospectus. We incorporate by reference into this prospectus the documents listed below (other than portions of

these documents furnished under Item 2.02 or Item 7.01 of a Current Report on Form 8-K):

•Our Annual Report on Form 10-K for the year ended December 31, 2025, filed with the SEC on February

26, 2026 (including information specifically incorporated by reference into such Annual Report on Form

10-K from our Proxy Statement for our 2026 Annual Meeting of Stockholders filed with the SEC on April

17, 2026);

•Our Quarterly Report on Form 10-Q for the quarter ended March 31, 2026, filed with the SEC on April 29,

2026;

•Our Current Report on Form 8-K, filed with the SEC on April 22, 2026; and

•The description of our Class A common stock set forth in Exhibit 4.3 to our Annual Report on Form 10-K

for the fiscal year ended December 31, 2025, filed with the SEC on February 26, 2026.

Any statement contained in a document incorporated by reference herein will be deemed to be modified or

superseded for purposes of this prospectus to the extent that a statement contained in this prospectus or any other

subsequently filed document that is incorporated by reference herein modifies or supersedes the statement. Any

statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of

this prospectus.

Our filings with the SEC, including our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q,

Current Reports on Form 8-K and amendments to those reports, are available free of charge on our website (https://

investors.neptuneflood.com/) as soon as reasonably practicable after they are filed with, or furnished to, the SEC.

Our website and the information contained on that site, or connected to that site, are not incorporated into and are

not a part of this prospectus except for the documents specifically incorporated by reference as noted above. You

may also obtain a copy of these filings at no cost by writing or telephoning us at the following address:

Investor Relations

400 6 th Street S., Suite 2

Tel. No. (727)387-6467

Joint Book-Runners

Morgan Stanley

J.P. Morgan

Goldman Sachs & Co. LLC

, 2026

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Part II

Information Not Required in Prospectus

Item 13. Other Expenses of Issuance and Distribution

The following table sets forth the costs and expenses in connection with the sale of the shares of common stock

being registered hereby. All amounts are estimates except for the SEC registration fee and the FINRA filing fee and

the listing fee.

Item 14. Indemnification of Directors and Officers.

Section 145 of the DGCL authorizes a corporation to indemnify its directors and officers against liabilities

arising out of actions, suits and proceedings to which they are made or threatened to be made a party by reason of

the fact that they have served or are currently serving as a director or officer to a corporation. The indemnity may

cover expenses (including attorneys’ fees) judgments, fines, and amounts paid in settlement actually and reasonably

incurred by the director or officer in connection with any such action, suit or proceeding. Section 145 permits

corporations to pay expenses (including attorneys’ fees) incurred by directors and officers in advance of the final

disposition of such action, suit or proceeding. In addition, Section 145 provides that a corporation has the power to

purchase and maintain insurance on behalf of its directors and officers against any liability asserted against them and

incurred by them in their capacity as a director or officer, or arising out of their status as such, whether or not the

corporation would have the power to indemnify the director or officer against such liability under Section 145.

As permitted by the DGCL, our amended and restated certificate of incorporation contains provisions that

eliminate the personal liability of its directors and certain of its officers for monetary damages for any breach of

fiduciary duties as a director or officer, except liability for the following:

•any breach of the director’s duty of loyalty to us or our stockholders;

•acts or omissions not in good faith or that involve intentional misconduct or a knowing violation of law;

•for directors, any under Section 174 of the DGCL (regarding unlawful dividends and stock purchases);

•any transaction from which the director derived an improper personal benefit; or

•for officers, for any action by or in the right of the Company.

As permitted by the DGCL, our amended and restated bylaws provide that:

•we are required to indemnify our directors and officers to the fullest extent permitted by the DGCL, as it

now exists or may in the future be amended;

•we may indemnify our other employees and agents as set forth in the DGCL;

•we are required to advance expenses, as incurred, to our directors and officers in connection with a legal

proceeding to the fullest extent permitted by the DGCL, subject to limited exceptions; and

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•the rights conferred in the bylaws are not exclusive.

We have entered, and intend to continue to enter, into separate indemnification agreements with our current

directors and executive officers to provide these directors and executive officers additional contractual assurances

regarding the scope of the indemnification set forth in our amended and restated certificate of incorporation and

amended and restated bylaws and to provide additional procedural protections. The indemnification provisions in

our amended and restated certificate of incorporation, amended and restated bylaws and the indemnification

agreements entered into or to be entered into between us and each of our directors and executive officers may be

sufficiently broad to permit indemnification of our directors and executive officers for liabilities arising under the

Securities Act.

We have directors’ and officers’ liability insurance that covers certain liabilities of our directors and officers

arising out of claims based on acts or omissions in their capacities as directors or officers.

The underwriting agreement filed as Exhibit 1.1 to this registration statement provides for indemnification of us

and our directors and officers by the underwriters against certain liabilities under the Securities Act and the

Exchange Act.

Item 15. Recent Sales of Unregistered Securities.

Set forth below is information regarding shares of capital stock issued by us since January 1, 2023, that were not

registered under the Securities Act. Also included is the consideration, if any, received by us for such shares and

information relating to the section of the Securities Act or SEC rule under which exemption from registration was

claimed. All information below has been adjusted for the 10-for-1 stock split of our capital stock that was effected

on September 9, 2025.

•From January 1, 2023, to September 26, 2025, we granted stock options to purchase an aggregate of

18,088,500 shares of our Class A common stock under our Amended and Restated 2025 Stock Plan, with

a weighted average exercise price of$7.52 per share, of which 448,500 options were forfeited prior to the

IPO in accordance with their terms,2,835,000 options were exercised prior to the IPO with a weighted

average exercise price of$5.50,5,880,000 options terminated at the time of the IPO in accordance with

their terms and the remainder are fully vested.

•On May 10, 2023, we issued and sold an aggregate of 41,850,000 shares of our convertible preferred stock,

at a purchase price of $5.495 per share for an aggregate purchase price of $230 million.

•On April 10, 2025, pursuant to our corporate reorganization, Neptune Holdings issued 93,350,000 shares of

its common stock and 41,850,000 shares of its convertible preferred stock to the prior holders of shares of

common stock and convertible preferred stock, respectively, of Neptune Flood. Pursuant to the

reorganization, (i) each issued and outstanding share of common stock of Neptune Flood was converted

into one share of common stock of Neptune Holdings, (ii) each issued and outstanding share of convertible

preferred stock of Neptune Flood was converted into one share of convertible preferred stock of Neptune

Holdings, and (iii) the issued, outstanding and unexercised portions, whether or not vested or exercisable,

of all options to purchase Neptune Flood common stock granted under the Neptune Flood stock plan were

assumed by Neptune Holdings and thereafter became exercisable for the same number of shares of

common stock of Neptune Holdings.

None of the foregoing transactions involved any underwriters, underwriting discounts or commissions, or any

public offering. The sales of the above securities were deemed to be exempt from registration under the Securities

Act in reliance upon Section 4(a)(2) of the Securities Act (or of Regulation D promulgated thereunder) or pursuant

to benefit plans and contracts relating to compensation as provided under Rule 701. The recipients of the securities

in each of these transactions represented their intentions to acquire the securities for investment only and not with a

view to or for sale in connection with any distribution thereof, and appropriate legends were placed upon the stock

certificates issued in these transactions.

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Item 16. Exhibits and Financial Statement Schedules.

(a) Exhibits.

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• Filed herewith.

• Indicates a management contract or compensatory plan or arrangement.

⸸ Certain of the exhibits and schedules to this exhibit have been omitted in accordance with Regulation S-K Item 601(a)(5). The Company

agrees to furnish a copy of all omitted exhibits and schedules to the SEC upon its request.

(b) Financial Statement Schedules.

All other financial statement schedules are omitted because they are not applicable or because the information is

included in the Company’s audited consolidated financial statements or related notes.

Item 17. Undertakings.

The undersigned Registrant hereby undertakes to provide to the underwriters at the closing specified in the

underwriting agreement certificates in such denominations and registered in such names as required by the

underwriters to permit prompt delivery to each purchaser.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers

and controlling persons of the Registrant pursuant to provisions described in Item 14 above, or otherwise, the

Registrant has been advised that in the opinion of the SEC such indemnification is against public policy as expressed

in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such

liabilities (other than the payment by the Registrant of expenses incurred or paid by a director, officer or controlling

person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director,

officer or controlling person in connection with the securities being registered, the Registrant will, unless in the

opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate

jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities

Act and will be governed by the final adjudication of such issue.

The undersigned Registrant hereby undertakes that:

(1)for purposes of determining any liability under the Securities Act, the information omitted from the

form of prospectus filed as part of this registration statement in reliance upon Rule 430A and

contained in a form of prospectus filed by the Registrant pursuant to Rule 424(b)(1) or (4) or

497(h) under the Securities Act shall be deemed to be part of this registration statement as of the time

it was declared effective.

(2)for the purpose of determining any liability under the Securities Act, each post-effective amendment

that contains a form of prospectus shall be deemed to be a new registration statement relating to the

securities offered therein, and the offering of such securities at that time shall be deemed to be the

initial bona fide offering thereof.

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