Note 9 - Shareholders' Equity

9 Months Ended

Sep. 30, 2021

Notes to Financial Statements

Stockholders' Equity Note Disclosure [Text Block]

Common Stock Purchase Agreement

On October 24, 2019, the Company entered into a Common Stock Purchase Agreement with Ninteenth Investment Company LLC, an affiliate of Mubadala Investment Company PJSC (the “Purchaser”).  During the three and nine months ended September 30, 2021, the Company issued an additional 399 thousand and 798 thousand shares of Company common stock, respectively, to the Purchaser pursuant to the terms of the Common Stock Purchase Agreement.

At-the-Market Program

In August 2021, the Company entered into an at-the-market sales agreement with Virtu Americas LLC (“Virtu”) pursuant to which the Company may sell shares of Company common stock from time to time through Virtu acting as sales agent, for aggregate proceeds of up to $50 million.  During the three and nine months ended September 30, 2021, the Company sold approximately 0.1 million shares for proceeds of approximately $0.4 million.

Common Stock Warrants

During the three months ended September 30, 2021, Common Stock Warrants were exercised by certain holders of Series A Preferred Stock and Series B Preferred Stock.  In connection with the exercises of Common Stock Warrants, the Company issued an aggregate of approximately 1.5 million shares of Company common stock.