Note 5 - Stockholders' Equity and Common Stock Warrants

9 Months Ended

Sep. 30, 2021

Notes to Financial Statements

Stockholders' Equity Note Disclosure [Text Block]

5. Stockholders' Equity and Common Stock Warrants

February 2021 Common Stock Offering

In February 2021, the Company completed the February 2021 Offering in which it offered and sold 33,658,538 shares of its common stock in an underwritten, public offering for a purchase price to the public of $1.025 per share, inclusive of shares offered and sold pursuant to the exercise-in-full by the underwriter of its 30-day option to purchase additional shares. The February 2021 Offering resulted in aggregate net proceeds to the Company of $31.1 million, after deducting underwriting commissions, discounts, and expenses but prior to deducting other offering costs. In addition, at the closings of the February 2021 Offering, the Company issued to designees of the underwriter of the transaction warrants to purchase up to an aggregate of 1,682,927 shares of common stock to designees. The underwriter warrants have an exercise price of $1.28125 per share and a term of five years from the date of issuance.

 Common Stock Warrants

As of September 30, 2021, the Company had the following warrants outstanding to acquire shares of its common stock:

	Outstanding		Range of exercise price per share			Expiration dates
Common stock warrants issued in 2017 related to Series A convertible preferred stock offering		903,870		$33.30		March 2022
Common stock warrants issued in 2018 related to the January 2018 Offering		1,181,421	$12.00	-	$15.00	January 2023
Common stock warrants issued related to the May 2019 Offering		1,382,913	$5.00	-	$6.11875	May and December 2024
Common stock warrants issued related to the November 2019 Offering		213,570		$0.35		November 2024
Common stock warrants issued related to the December 2019 Offering		313,339	$0.4335	-	$0.6981	December 2024 and June 2025
Common stock warrants issued related to the May 2020 Offering		571,429		$1.31		May 2025
Common stock warrants issued related to May 2020 Investor Warrant Exercise		250,000		$0.5938		November 2025
Common stock warrants issued related to the February 2021 Offering		1,682,927		$1.28		February 2026
		6,499,469

During the nine months ended September 30, 2021, 53,570 warrants expired and 4,230,000 warrants were exercised for aggregate proceeds of approximately $2.2 million.