We have three share-based compensation plans that are administered by the Compensation Committee of the Board of Directors. We have (a) an Employee Stock Incentive Plan for officers, other employees, consultants and independent contractors under which we have granted options and restricted stock units to officers and other employees, (b) an Employee Stock Purchase Plan under which shares of our common stock may be acquired by employees at discounted prices, and (c) a Non-Employee Director Stock Plan that provides for automatic grants of restricted shares of our common stock to non-employee directors. New shares of our common stock are issued upon stock option exercises, vesting of restricted stock units, issuances of shares to board members and issuances of shares under the Employee Stock Purchase Plan.

As of March 31, 2020, there were 185,351 shares of common stock reserved in the aggregate for issuance pursuant to future awards under our Employee Stock Incentive Plan and 558,654 shares of common stock reserved in the aggregate for issuance pursuant to outstanding awards under such plan. Although our Compensation Committee has authority to issue options, restricted stock, restricted stock units, share grants and other share-based benefits under our Employee Stock Incentive Plan, to date only restricted stock units and stock options have been granted under the plan. Options have been granted at an option price per share equal to the market value of our common stock on the date of grant, vest over a four year period and expire seven years after the date of grant. Restricted stock units vest over a four year period and entitle the holders to one share of our common stock for each restricted stock unit. Reserved shares underlying outstanding awards, including options and restricted stock units, that are forfeited are available under the Employee Stock Incentive Plan for future grant.

As of March 31, 2020, there were 52,000 shares of common stock reserved in the aggregate for issuance pursuant to future restricted share grants under our Non-Employee Director Stock Plan and 16,000 shares of common stock reserved in the aggregate for issuance pursuant to outstanding stock option awards under our Non-Employee Director Stock Plan (which previously authorized the granting of stock options to non-employee directors). Under the terms of the plan, each non-employee director receives annual restricted share grants of 2,000 shares of our common stock on the date of each annual meeting at which such director is elected to serve on the board. The annual restricted share grants of common stock vest in four equal quarterly installments during the year after the grant date, provided the non-employee director is still serving as a director on the applicable vesting date.

On the date of our 2019 annual meeting, we issued a total of 8,000 shares of our common stock to our non-employee directors, which were restricted as specified in the Non-Employee Director Stock Plan. The shares granted at the 2019 annual meeting had an aggregate fair market value on the date of grant equal to $138,000 (grant date fair value of $17.26 per share). As of March 31, 2020, 6,000 of these shares were vested. The aggregate fair value of the 2,000 unvested shares based on the closing price of our common stock on March 31, 2020 was $34,000.

The following is a summary of stock option activity in the three months ended March 31, 2020:


	Options Outstanding		Weighted Average Exercise Price Per Share
Outstanding, December 31, 2019	520,513		$	12.25
Granted	—		—
Exercised	(10,063	)	8.44
Expired	—		—
Forfeited	—		—
Outstanding, March 31, 2020	510,450		$	12.33

Exercisable, March 31, 2020	370,876		$	10.39

The intrinsic value of an option is the amount by which the market price of the underlying common stock exceeds the option's exercise price. For options outstanding at March 31, 2020, the weighted average remaining contractual term of all outstanding options was 3.4 years and their aggregate intrinsic value was $2.9 million. At March 31, 2020, the weighted average remaining contractual term of options that were exercisable was 2.5 years and their aggregate intrinsic value was $2.8 million. The aggregate intrinsic value of stock options exercised was $140,000 in the three months ended March 31, 2020 and $57,000 in the three months ended March 31, 2019. We received proceeds from stock option exercises of $85,000 in the three months ended March 31, 2020 and $59,000 in the three months ended March 31, 2019. No stock options vested in the three months ended March 31, 2020.

Restricted shares are granted under our Non-Employee Director Stock Plan. Restricted stock units are granted under our Employee Stock Incentive Plan. No restricted shares or restricted stock units were granted in the three months ended March 31, 2020. The aggregate fair value of outstanding restricted shares and restricted stock units based on the closing share price of our common stock as of March 31, 2020 was $1.1 million. The aggregate fair value of restricted shares and restricted stock units that vested, based on the closing price of our common stock on the vesting date, was $45,000 in the three months ended March 31, 2020 and $43,000 in the three months ended March 31, 2019.

The following is a summary of activity in restricted shares and restricted stock units in the three months ended March 31, 2020:

Restricted shares and restricted stock units	Shares		Weighted Average Grant Date Fair Value
Non-vested at December 31, 2019	68,204		$	17.39
Granted	—		—
Vested	(2,000	)	17.26
Forfeited	—		—
Non-vested at March 31, 2020	66,204		$	17.39

We have an Employee Stock Purchase Plan available to eligible U.S. employees. Under the terms of the plan, eligible employees may designate from 1% to 10% of their compensation to be withheld through payroll deductions, up to a maximum of $6,500 in each plan year, for the purchase of common stock at 85% of the lower of the market price on the first or last day of the offering period (which begins on August 1st and ends on July 31st of each year). No shares were purchased under this plan in the three months ended March 31, 2020 or the three months ended March 31, 2019. As of March 31, 2020, 156,688 shares remain available for future purchase under the Employee Stock Purchase Plan.

All share-based compensation awarded to our employees and non-employee directors, including grants of stock options, restricted stock units and restricted shares, are required to be recognized as an expense in our consolidated statements of operations based on the grant date fair value of the award. We utilize the straight-line method of expense recognition over the award's service period for our graded vesting options. The fair value of stock options has been determined as of the date of grant using the Black-Scholes model. We have classified employee share-based compensation within our statements of operations in the same manner as our cash-based employee compensation costs.

Pre-tax share-based compensation expense in the three months ended March 31, 2020 totaled $272,000, and included $114,000 for stock options, $23,000 for our Employee Stock Purchase Plan, $101,000 for restricted stock units and $34,000 for restricted shares.

Pre-tax share-based compensation expense in the three months ended March 31, 2019 totaled $244,000, and included $107,000 for stock options, $29,000 for our Employee Stock Purchase Plan, $76,000 for restricted stock units and $32,000 for restricted shares.

At March 31, 2020, the total unrecognized compensation cost related to non-vested share-based compensation arrangements was $2.1 million and the related weighted average period over which such cost is expected to be recognized is 2.79 years.