Note 8 - Warrants

3 Months Ended

Mar. 31, 2023

8. Warrants

The activity related to warrants during the three months ended March 31, 2023, is summarized as follows:

	Common Stock from Warrants		Weighted- average Exercise Price (per share)
Outstanding at December 31, 2022		7,824,933	$	1.72
Pre-funded warrants exercised		2,632,898	$	0.0001
Outstanding at March 31, 2023		5,192,035	$	2.59
Exercisable at March 31, 2023		964,983	$	4.89

The pre-funded warrants issued in December 2022 to purchase 2,632,898 shares of common stock, or the 2022 Pre-Funded Warrants, were exercised in full in the three months ended March 31, 2023. The common warrants issued in December 2022 to purchase an aggregate of 4,227,052 shares of common stock, or the 2022 Warrants, were accounted for by the Company as a liability. At March 31, 2023, the 2022 Warrants were valued at approximately $1.8 million, using the Black-Scholes option pricing model as follows: exercise price of $2.07 per share, stock price of $0.658 per share, expected life of 6 years, volatility of 97.06%, a risk-free rate of 3.58% and 0% expected dividend yield. See Note 2, “Investments and Fair Value Measurement” and Note 11, “Subsequent Events”.