Note 7 - Stockholders' Equity and Common Stock Warrants

12 Months Ended

Dec. 31, 2022

Notes to Financial Statements

Stockholders' Equity Note Disclosure [Text Block]

7. Stockholders' Equity and Common Stock Warrants

Common Stock Warrants

As of December 31, 2022, 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 2018 related to the January 2018 Offering		23,639	$599.71	-	$749.76	January 2023
Common stock warrants issued related to the May 2019 Offering		27,648	$250.09	-	$306.04	May and December 2024
Common stock warrants issued related to the November 2019 Offering		4,269		$17.51		November 2024
Common stock warrants issued related to the December 2019 Offering		6,264	$21.68	-	$34.92	December 2024 and June 2025
Common stock warrants issued related to the May 2020 Offering		11,424		$65.65		March 2025
Common stock warrants issued related to the May 2020 Investor Warrant Exercise		4,998		$29.70		November 2025
Common stock warrants issued related to the February 2021 Offering		33,649		$64.08		February 2026
		111,891

During the years ended December 31, 2022 and 2021, 18,077 and 1,071 warrants expired, respectively.