ClearSign Technologies Corporation (NASDAQ:CLIR) ("ClearSign" or the "Company"), a leader in advanced combustion and sensing technologies that help industrial operators dramatically reduce emissions, increase efficiency and support the use of cleaner fuels including hydrogen, today announces the completion of a private placement (the "Placement") of 500,000 shares of its common stock, par value $0.001 per share, with an existing stockholder at a price of $3.54 per share, the average closing price reported on Nasdaq for the five trading days ending on June 21, 2026, for gross proceeds of $1,770,000. The Placement closed on July 22, 2026.

ClearSign intends to use the net proceeds from the Placement for working capital, research and development, marketing and sales, and general corporate purposes.