Note 5 - Equity

3 Months Ended

Mar. 31, 2022

Notes to Financial Statements

Stockholders' Equity Note Disclosure [Text Block]

5. Equity

2022 Stock Issuances

The Company did not make any stock issuances in the three months ended March 31, 2022.

2021 Stock Issuances

In February 2021, the Company entered into an underwritten public offering for the sale by the Company of 14,273,684 shares of its common stock at a public offering price of $4.75 per share and granted the underwriters a 30-day option to purchase up to an additional 2,141,052 shares of common stock offered in the public offering, which was exercised. The Company received total proceeds of $78.0 million, prior to deducting the underwriting discount and other estimated offering expenses. In January 2021 the Company issued 468,684 shares for gross proceeds of $2.9 million using the Company's 2020 At The Market Agreement (2020 ATM Agreement) with Oppenheimer & Co., Inc. The Company terminated the 2020 ATM Agreement on February 2, 2021. 

Stock-Based Compensation and Outstanding Awards

The 2015 Stock Plan provides for the grant of stock options, stock awards, stock unit awards, and stock appreciation rights. As of March 31, 2022, there were 19,961 shares remaining to be issued under the 2015 Stock Plan. 

Stock-based compensation for the three months ended March 31, 2022 and 2021, respectively (in thousands):

	Three Months Ended March 31,
	2022		2021
General and administrative	$	361	$	309
Research and development		166		96
Total stock-based compensation expense	$	527	$	405

During the three months ended March 31, 2022, the Company granted 21,667 stock options with a weighted average exercise price of $1.61 per share that vest over a three to four-year period from the grant date on a straight-line basis over the requisite service period for each separately vesting portion of the award as if the award was, in substance, multiple awards.