Note 9 - Warrants

12 Months Ended

Dec. 31, 2021

Notes to Financial Statements

Warrants [Text Block]

9. Warrants

In March 2014, pursuant to a to a registered public offering and note conversion agreement with certain note holders, the Company issued warrants to purchase 6,910,283 shares of common stock at $4.75 per share. The warrants had an original expiration date of March 2021.

In May 2016, in connection with a credit facility, the Company issued a warrant to purchase 550,000 shares of common stock at $1.75 per share. The warrant was immediately exercisable and had an original expiration date of May 2021.

In May 2020, the Company entered into separate warrant exercise agreements with WAVI Holding AG and Taurus4757 GmbH pursuant to which the warrant holders immediately exercised their respective warrants via a “cashless” exercise as agreed to by the Company. As a result of the cashless exercise, the Company issued an aggregate of 2,747,970 shares of Company common stock upon cashless exercise of an aggregate of 3,871,405 warrants.

In March 2021, all remaining outstanding warrants were exercised via a “cashless” exercise. As a result of the cashless exercise, the Company issued an aggregate of 70,030 shares of Company common stock upon cashless exercise of an aggregate of 79,100 warrants.

The following table summarizes warrant activity for the years ended December 31, 2021, 2020, and 2019:

	2021					2020					2019
	Shares			Wtd. Avg. Exercise Price		Shares			Wtd. Avg. Exercise Price		Shares			Wtd. Avg. Exercise Price
Outstanding at beginning of year		79,100		$	4.75		3,959,005		$	4.33		4,080,005		$	4.35
Exercised		(79,100	)		4.75		(3,879,905	)		4.33		(121,000	)		4.75
Outstanding and exercisable at end of year		-		$	-		79,100		$	4.75		3,959,005		$	4.33