Filed Pursuant to Rule 424(b)(5)

Registration No. 333-297143

PROSPECTUS SUPPLEMENT NO. 2

(to Prospectus dated August 11, 2026)

Up to 48,055,843 Shares of Common Stock

Up to 3,535,082 Shares of Common Stock Issuable Upon Exercise of Warrants

This prospectus supplement supplements the prospectus dated August 11, 2026 (the “Prospectus”), which forms a part of our registration statement on Form S-1 (No. 333-297143). This prospectus supplement is being filed to update and supplement the information in the Prospectus with the information contained in our Current Report on Form 8-K, filed with the Securities and Exchange Commission on September 21, 2026 (the “Current Report”). Accordingly, we have attached the Current Report to this prospectus supplement.

The Prospectus and this prospectus supplement relate to the offering and resale by the selling stockholders identified herein of up to 51,590,925 shares of common stock, par value $0.0001 per share, of Matternet, Inc. (fka Los Altos Ventures Corp.) (“Matternet” or the “Company”), consisting of:

We will not receive any proceeds from the sale of the shares of common stock by the selling stockholders, except with respect to amounts that may be received by us upon the cash exercise of the Placement Agent Warrants, the Bridge Warrants and the Legacy Warrants. We will bear all costs, expenses and fees in connection with the registration of these securities, including with regard to compliance with state securities or “blue sky” laws.

As disclosed in the Current Report, on September 21, 2026, our common stock became qualified for trading on the OTCQB Venture Market under the ticker symbol “MTTN”.

This prospectus supplement updates and supplements the information in the Prospectus and is not complete without and may not be delivered or utilized except in combination with, the Prospectus, including any amendments or supplements thereto. This prospectus supplement should be read in conjunction with the Prospectus and if there is any inconsistency between the information in the Prospectus and this prospectus supplement, you should rely on the information in this prospectus supplement.

We are an “emerging growth company” and a “smaller reporting company” as defined under the federal securities laws and, as such, are eligible for reduced public company reporting requirements.

Investing in our common stock involves a high degree of risk. Before making an investment decision, please read “Risk Factors” beginning on page 6 of the Prospectus, and under similar headings in any amendments or supplements to the Prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the Prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is September 21, 2026

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): September 21, 2026

MATTERNET, INC.

(Exact name of Registrant as Specified in Its Charter)

(Registrant’s telephone number, including area code): (650) 260-2727

N/A

(Former Name or Former Address, if Changed Since Last Report)

Securities registered pursuant to Section 12(b) of the Act: None

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

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 ☒

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 21, 2026, Matternet, Inc. announced that our common stock has qualified to trade on the OTCQB Venture Market and will commence trading on September 21, 2026 under the ticker symbol “MTTN”.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.