SMITH MICRO SOFTWARE, INC.

As filed with the Securities and Exchange Commission on May 8, 2026

Registration Statement No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORMS-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Smith Micro Software, Inc.

(Exact name of registrant as specified in its charter)

5800 Corporate Drive

Pittsburgh, PA 15237

(412)837-5300

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Timothy C. Huffmyer

Chief Executive Officer

Smith Micro Software, Inc.

5800 Corporate Drive

Pittsburgh, PA 15237

(412) 837-5300

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Brian Novosel, Esq.

Jennifer Minter, Esq.

Buchanan Ingersoll & Rooney PC

Union Trust Building

501 Grant Street, Suite 200

Pittsburgh, PA 15219

(412) 562-8800

Approximate date of commencement of proposed sale to the public: From time to time after this registration statement becomes effective.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933 check the following box: ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please 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(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-accelerated filer, 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-2 of the Exchange Act.

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 registrant is filing a combined prospectus in this registration statement pursuant to Rule 429 under the Securities Act of 1933, as amended (the “Securities Act”) in order to satisfy the requirements of the Securities Act and the rules and regulations thereunder for this offering and the offering registered under the registrant’s registration statement on Form S-1 (File No. 333-291949) (the “Prior Registration Statement”), which was declared effective on December 12, 2025. The combined prospectus in this registration statement, upon effectiveness, shall act as Post-Effective Amendment No. 1 on Form S-1 to the Prior Registration Statement and contains an updated prospectus relating to the offering and sale of shares of the registrant’s Common Stock issuable upon exercise of warrants issued pursuant to those certain Note Purchase Agreements dated September 11, 2025 and September 29, 2025 that were originally registered under the Prior Registration Statement.

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE

This prospectus forms a part of a new registration on Form S-1 and also constitutes Post-Effective Amendment No. 1 to the Registration Statement on Form S-1 of Smith Micro Software, Inc. (the “Company”) (File No. 333-291949), which was declared effective on December 12, 2025 (the “Prior Registration Statement”), and is being filed pursuant to the undertakings in Item 17 of the Prior Registration Statement to update and supplement the information contained therein. Accordingly, this registration statement contains a combined prospectus (the “Combined Prospectus”) pursuant to Rule 429 under the Securities Act relating to the resale from time to time by the selling stockholders named in this prospectus or their permitted transferees (the “Selling Stockholders”) of:

Pursuant to Rule 416 under the Securities Act, the Prior Registration Statement also registered, and this registration statement is similarly registering, an indeterminate number of additional shares of Common Stock issuable upon stock splits, stock dividends or other distributions, recapitalizations or similar events with respect to the Common Stock.

Pursuant to Rule 429(b) under the Securities Act, upon effectiveness, this registration statement shall constitute Post-Effective Amendment No. 1 to the Prior Registration Statement and is being filed to update the Prior Registration Statement to include the securities discussed in (A) and (B) above. Such Post-Effective Amendment shall hereafter become effective concurrently with the effectiveness of this registration statement in accordance with Section 8(c) of the Securities Act.

The information in this prospectus is not complete and may be changed. The selling stockholders may not sell these securities pursuant to this prospectus until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

Subject to Completion, Dated May 8, 2026

PRELIMINARY PROSPECTUS

7,190,188 Shares of Common Stock Issuable Upon Conversion of Notes

11,034,437 Shares of Common Stock Issuable Upon Exercise of Warrants

This prospectus relates to the resale or other disposition from time to time by the selling stockholders identified herein (each, a “Selling Stockholder” and, together, the “Selling Stockholders”) or their pledgees, assignees, distributees and successors-in-interest from time to time, of up to 7,190,188 shares of Company Common Stock, par value $0.001 per share (“Common Stock”) issuable as follows:

The September 11 Warrants, the September 29 Warrants, the February Warrants, and the March Warrants are collectively referred to herein as the “Warrants.” The September 11 Warrant shares, the September 29 Warrant Shares, the February Warrant Shares and the March Warrant Shares, are collectively referred to herein as the “Warrant Shares.” The September 11 Offering, the September 29 Offering, the February Offering and the March Notes and Warrants Offering are collectively referred to herein as the “Offerings.”

We are registering the offer and sale of Common Stock on behalf of the Selling Stockholders to satisfy certain registration rights that we have granted to the Selling Stockholders.

Each Selling Stockholder may, from time to time, sell, transfer, or otherwise dispose of any or all the Common Stock on any stock exchange, market, or trading facility on which shares of our Common Stock are traded or in private transactions. These dispositions may be at fixed prices, at prevailing market prices at the time of sale, at prices related to the prevailing market price, at varying prices determined at the time of sale, or at negotiated prices.

The Selling Stockholders will bear all commissions and discounts, if any, attributable to the sales of Common Stock. We will bear all other costs, expenses, and fees in connection with the registration of the Common Stock. See “Plan of Distribution” which begins on page 19 of this prospectus.

We are not offering any shares of our Common Stock for sale under this prospectus. We will not receive any of the proceeds from the sale or other disposition of our Common Stock by the Selling Stockholders. However, we may receive proceeds of up to approximately $7.5 million if all the Warrants held by the Selling Stockholders are exercised for cash, based on the current per share exercise prices of the Warrants. Our Common Stock is listed on the Nasdaq Capital Market under the symbol “SMSI.” On May 7, 2026, the last reported sale price of our Common Stock on the Nasdaq Capital Market was $0.8426.

INVESTING IN OUR COMMON STOCK INVOLVES A HIGH DEGREE OF RISK. YOU SHOULD CAREFULLY CONSIDER THE RISKS AND UNCERTAINTIES IN THE SECTION ENTITLED “RISK FACTORS” BEGINNING ON PAGE 11 OF THIS PROSPECTUS AND IN THE OTHER DOCUMENTS THAT ARE INCORPORATED BY REFERENCE BEFORE PURCHASING ANY OF THE SHARES OFFERED BY THIS PROSPECTUS.

We may amend or supplement this prospectus from time to time by filing amendments or supplements as required. You should read the entire prospectus and any amendments or supplements carefully before you make your investment decision.

Neither the Securities and Exchange Commission (the“SEC”) nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is _____ __, 2026