Company (Nasdaq: SCWO) terminates earlier $15.1M ATM stock offering

Rhea-AI Filing Summary

The company is ending a prior at-the-market stock sale program with Lake Street Capital Markets. That earlier agreement allowed sales of up to $15,100,000 of common stock over time. As of December 23, 2025, the company has sold $9.3 million of common stock under this program, and this prospectus supplement formally terminates that continuous offering as of that date. The company has entered into a new sales agreement with Lake Street for a new program, but this document focuses on closing out the old one. The company’s common stock trades on the Nasdaq Capital Market under the symbol SCWO, and the last reported sale price on December 22, 2025 was $0.24 per share.

Filed Pursuant to Rule 424(b)(5)

Registration No. 333-268942

PROSPECTUS SUPPLEMENT

(To Prospectus dated December 30, 2022)

We previously entered into an at-the-market issuance sales agreement (the “ATM Agreement”) with Lake Street Capital Markets, LLC (“Lake Street”) relating to the sale of up to $15,100,000 of shares of our common stock, par value $0.0001 per share (the “Common Stock”), from time to time through Lake Street acting as our sales agent.

As of December 23, 2025, we have sold $9.3 million of our shares of Common Stock under the ATM Agreement pursuant to our prospectus supplement dated June 6, 2025 (the “Prospectus Supplement”). This prospectus supplement should be read in conjunction with the Prospectus Supplement, and is qualified by reference thereto, except to the extent that the information herein amends or supersedes the information contained in the Prospectus Supplement. This prospectus supplement is not complete without, and may only be delivered or utilized in connection with, the Prospectus Supplement, and any future amendments or supplements thereto.

We have replaced the ATM Agreement with a sales agreement for a new program with Lake Street, and the purpose of this prospectus supplement is to terminate the continuous offering by us under the Prospectus Supplement effective on December 23, 2025. We will not make any further sales of our shares of Common Stock pursuant to the Sales Agreement.

Our common stock is listed on The Nasdaq Capital Market under the symbol “SCWO.” The last reported sale price of our common stock on December 22, 2025, was $0.24 per share.

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

December 23, 2025

FAQ

What change does SCWO disclose in its at-the-market stock sales program?

The company is terminating its prior at-the-market stock offering program with Lake Street Capital Markets. This prospectus supplement ends the continuous offering under the earlier prospectus supplement effective December 23, 2025.

How much stock has SCWO sold under its prior at-the-market program?

As of December 23, 2025, the company has sold $9.3 million of its common stock under the at-the-market program governed by the previous prospectus supplement.

What was the maximum size of SCWO's previous at-the-market offering?

The prior at-the-market issuance sales agreement with Lake Street Capital Markets allowed the sale of up to $15,100,000 of the company’s common stock over time.

Has SCWO put a new stock sales agreement in place with Lake Street?

Yes. The company states that it has replaced the earlier at-the-market issuance sales agreement with a new sales agreement for a new program with Lake Street Capital Markets.

Will SCWO sell any more shares under the terminated at-the-market agreement?

No. The company states that it will not make any further sales of its common stock pursuant to the prior sales agreement and related prospectus supplement.

On which exchange does SCWO trade and what was the recent price?

The company’s common stock is listed on The Nasdaq Capital Market under the symbol SCWO. The last reported sale price on December 22, 2025 was $0.24 per share.