At September 30, 2023 and December 31, 2022, there were zero and 20,929 warrants outstanding, respectively, which were issued in conjunction with a public equity offering in January 2018. All outstanding warrants expired on January 17, 2023.

At September 30, 2023, the Company has reserved 76,648 and 34,926 shares of common stock issuable upon the exercise of outstanding stock options and unvested stock awards, respectively under its 2006 and 2016 Equity Incentive Plans. An additional 68,296 shares of common stock are reserved for future equity awards under the 2016 Equity Incentive Plan.

A summary of the Company’s unvested stock awards for the nine months ended September 30, 2023, is as follows:


	Shares	Weighted ‎average grant ‎date fair value
Unvested at December 31, 2022	9,983	$	37.24
Granted	39,280		10.58
Vested	(13,342)		25.61
Forfeited	(995)		26.86
Unvested at September 30, 2023	34,926	$	11.99

During the nine months ended September 30, 2023 and 2022, the Company expensed $294 thousand and $294 thousand, respectively, related to the stock awards. At September 30, 2023, the balance of unearned share-based compensation to be expensed in future periods related to the stock awards is $286 thousand. The period over which the unearned share-based compensation is expected to be earned is approximately 1.7 years.


	Number of ‎options	Weighted ‎average ‎exercise price
Outstanding at December 31, 2022	42,033	$	71.69
Issued	36,654		7.20
Exercised	—		—
Forfeited	(1,585)		11.92
Expired	(454)		150.00
Outstanding at September 30, 2023	76,648	$	41.62
Exercisable at September 30, 2023	41,519	$	67.56

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. There were 36,654 stock options granted during the nine months ended September 30, 2023.

The total intrinsic value of all options outstanding was $0 at September 30, 2023 and December 31, 2022. The total intrinsic value of exercisable options was $0 at September 30, 2023 and December 31, 2022.

The following table summarizes information about options outstanding and exercisable at September 30, 2023:


Weighted ‎average exercise ‎price of outstanding ‎options	Number of ‎options ‎outstanding	Weighted ‎average remaining ‎estimated life ‎(in years)	Number of ‎options ‎exercisable
< $10.00	35,392	9.7	4,903
$20.00 - $50.00	35,487	6.3	31,081
$100.00 - $200.00	2,394	6.6	2,160
$200.00 - $500.00	3,375	2.4	3,375
	76,648		41,519

Total share-based compensation on stock options amounted to $130 thousand and $133 thousand for the nine months ended September 30, 2023 and 2022, respectively. At September 30, 2023, the balance of unearned share-based compensation to be expensed in future periods related to unvested share-based awards was $277 thousand. The period over which the unearned share-based compensation is expected to be earned is approximately 1.7 years.