Free Writing Prospectus - Filing Under Securities Act Rules 163/433 (fwp)

Issuer Free Writing Prospectus dated July 25, 2019

Filed Pursuant to Rule 433 under the Securities Act of 1933

Relating to the Preliminary Prospectus dated July 25, 2019

Registration Statement No. 333-232276

OBALON THERAPEUTICS, INC.

This free writing prospectus relates to, and should be read together with, the preliminary prospectus dated July 25, 2019 (the “Preliminary Prospectus”) included in Amendment No. 1 to the Registration Statement on Form S-1 (File No. 333-232276) (the “Registration Statement”) relating to a public offering of the common stock, and pre-funded warrants to purchase common stock, of Obalon Therapeutics, Inc. (the “Company”).

The Company has filed a registration statement (including a prospectus) with the Securities and Exchange Commission (the “SEC”) for the offering to which this communication relates. Before you invest, you should read the prospectus in Registration Statement and other documents the Company has filed with the SEC for more complete information about the Company and this offering. You may get these documents for free by visiting EDGAR on the SEC Web site at www.sec.gov. Alternatively, the Company, any underwriter or any dealer participating in the offering will arrange to send you the prospectus if you request it by email at prospectus@alliancecg.com .