On February 8, 2021, the Company completed a public offering of 14,950,000 Common Shares for net proceeds of approximately $119.1 million.

At March 31, 2022 and December 31, 2021, there were 418,441 warrants outstanding at an exercise price of $3.25, all of which were issued in conjunction with a public equity offering in January 2018. All remaining warrants have an expiration date of January 17, 2023.

At March 31, 2022, the Company has reserved 873,180 Common Shares issuable upon the exercise of outstanding stock options awarded under its 2006 and 2016 Equity Incentive Plans. An additional 465,984 Common Shares are reserved for future award and issuance under the 2016 Equity Incentive Plan.

A summary of the Company’s restricted Common Shares for the three months ended March 31, 2022, is as follows:


	Shares	Weighted ‎average grant ‎date fair value
Unvested at December 31, 2021	65,100	$	4.10
Granted	240,777		1.52
Vested	(121,232)		2.14
Forfeited	—		—
Unvested at March 31, 2022	184,645	$	2.03

During the three months ended March 31, 2022 and 2021, the Company expensed $168 thousand and $107 thousand, respectively related to the restricted stock awards. At March 31, 2022, the balance of unearned share-based compensation to be expensed in future periods related to the restricted stock awards is $347 thousand. The period over which the unearned share-based compensation is expected to be earned is approximately 2 years.


	Number of ‎options	Weighted ‎average ‎exercise price
Outstanding at December 31, 2021	663,425	$	4.31
Issued	209,755		1.55
Exercised	—		—
Forfeited	—		—
Expired	—		—
Outstanding at March 31, 2022	873,180	$	3.65
Exercisable at March 31, 2022	624,075	$	4.31

Unless otherwise indicated, options issued to employees, members of the Board of Directors, and non-employees are vested daily over one to three years and are exercisable for a term of ten years from the date of issuance.

The fair values of stock option grants to employees and members of the Board of Directors during 2022 were measured on the date of grant using Black-Scholes, with the following weighted average assumptions:


		2022
Expected volatility		103%
Risk free interest rate		2.10%
Expected dividend yield		0%
Expected life (in years)		5

The weighted average fair value of stock options granted during the three months ended March 31, 2022 was $1.12.

The total intrinsic value of all options outstanding was $73 thousand and $18 thousand at March 31, 2022, and December 31, 2021, respectively. The total intrinsic value of exercisable options was $1 thousand and $11 thousand at March 31, 2022 and December 31, 2021, respectively.

The following table summarizes information about options outstanding and exercisable at March 31, 2022:


Weighted ‎average exercise ‎price of outstanding ‎options	Number of ‎options ‎outstanding	Weighted ‎average remaining ‎estimated life ‎(in years)	Number of ‎options ‎exercisable
$1.52 - $2.50	732,288	7.9	503,779
$5.44 - $6.72	55,402	8.2	34,789
$7.50 - $10.80	16,403	2.1	16,403
$14.20 - $23.40	69,087	4.0	69,087
	873,180		624,058

Total share-based compensation on stock options amounted to $43 thousand and $22 thousand for the three months ended March 31, 2022 and 2021, respectively. At March 31, 2022, the balance of unearned share-based compensation to be expensed in future periods related to unvested share-based awards was $374 thousand. The period over which the unearned share-based compensation is expected to be earned is approximately 2 years.