Stockholders’ equity

Recent issuances

On March 21, 2019, the Company completed a public offering of 3,345,282 Common Shares. Net proceeds to the Company were $6.6 million after deducting discounts, fees, and expenses.

Warrants

The following table summarizes information about outstanding warrants at March 31, 2019:



	Number of warrant shares		Weighted average exercise price
Outstanding at December 31, 2018	1,745,868			$3.25
Exercised	(76,797	)	3.25
Outstanding at March 31, 2019	1,669,071			$3.25
Exercisable at March 31, 2019	1,669,071			$3.25

During the quarter ended March 31, 2019, the Company issued 76,797 Common Shares at $3.25 per share in conjunction with the exercise of warrants, with total proceeds of $250 thousand.

Share-based compensation

Restricted stock

A summary of the Company’s shares of restricted stock as of March 31, 2019, is as follows:



	Shares		Weighted average grant date fair value
Balance at December 31, 2018	8,867			$3.51
Granted	176,561		2.13
Vested	(40,623	)	2.21
Balance at March 31, 2019	144,805			$2.19

During the three months ended March 31, 2019 and 2018, the Company expensed $90,634 and $6,967, respectively, related to the restricted stock awards. At March 31, 2019, the balance of unearned share-based compensation to be expensed in future periods related to the restricted stock awards is $316,699. The period over which the unearned share-based compensation is expected to be earned is approximately 3.0 years.

Stock options

The Company’s option activity is summarized as follows:



	Number of options	Weighted average exercise price
Outstanding at December 31, 2018	339,964		$7.09
Issued	7,500	2.11
Outstanding at March 31, 2019	347,464		$6.98
Exercisable at March 31, 2019	326,382		$6.77

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

The weighted average fair value of stock options granted during the three months ended March 31, 2019, was $1.48. The fair value of stock option grants made were measured on the date of grant using Black-Scholes, with the following weighted average assumptions: expected volatility of 89%, risk free interest rate of 2.53%, expected dividend yield of 0.0%, and expected life of 5 years.

The total intrinsic value of all options outstanding was $600 and $0 at March 31, 2019, and December 31, 2018, respectively. The total intrinsic value of exercisable options was $43 and $0 at March 31, 2019, and December 31, 2018, respectively.

The following table summarizes information about options outstanding and exercisable at March 31, 2019:



Weighted average exercise price of outstanding options	Number of options outstanding	Weighted average remaining estimated life (in years)	Number of options exercisable	Weighted average exercise price of outstanding and exercisable options
$2.50 - $5.70	211,534	5.5	204,568
$6.90 - $9.60	53,175	3.5	53,175
$10.50 - $10.80	4,000	4.9	4,000
$14.20 - $23.40	78,755	7.0	64,639
	347,464		326,382	$6.77

Total share-based compensation on stock-option grants amounted to $47,864 and $41,579 for the three months ended March 31, 2019 and 2018, respectively. At March 31, 2019, the balance of unearned share-based compensation to be expensed in future periods related to unvested share-based awards was $74,780. The period over which the unearned share-based compensation is expected to be earned is approximately 1.0 years.