5. Stock-Based Compensation

Stock Incentive Plans

On March 20, 2007, the Company’s Board of Directors approved the 2007 Stock Incentive Plan (the “2007 Stock Plan”) for the issuance of up to 2,500,000 shares of common stock to be granted through incentive stock options, nonqualified stock options, stock appreciation rights, dividend equivalent rights, restricted stock, restricted stock units and other stock-based awards to officers, directors, other employees and consultants of the Company and its subsidiaries. This plan was approved by the stockholders on November 2, 2007. The exercise price of stock options under the 2007 Stock Plan was determined by the compensation committee of the Board of Directors, and should be equal to or greater than the fair market value of the Company’s common stock on the date the option was granted. The total number of shares of stock with respect to which stock options and stock appreciation rights may be granted to any one employee of the Company or a subsidiary during any one-year period under the 2007 Stock Plan could not exceed 250,000. Options become exercisable over various periods from the date of grant, and generally expire ten years after the grant date. As of June 30, 2017, there were 743,924 options issued and outstanding under the 2007 Stock Plan.

On November 2, 2010, the Board of Directors and stockholders adopted the 2010 Stock Incentive Plan (“2010 Stock Plan”) for the issuance of up to 3,000,000 shares of common stock to be granted through incentive stock options, nonqualified stock options, stock appreciation rights, dividend equivalent rights, restricted stock, restricted stock units and other stock-based awards to officers, directors, other employees and consultants of the Company and its subsidiaries. On October 22, 2013, the stockholders approved and adopted an amendment to the 2010 Stock Plan to increase the number of shares of the Company’s common stock reserved for issuance under the 2010 Stock Plan from 3,000,000 to 6,000,000. On May 15, 2015, the stockholders approved and adopted an amendment to the 2010 Stock Plan to increase the number of shares of the Company’s common stock reserved for issuance under the 2010 Stock Plan from 6,000,000 to 8,000,000. On August 25, 2016, the stockholders approved and adopted an amendment to the 2010 Stock Plan to increase the number of shares of the Company’s common stock reserved for issuance under the 2010 Stock Plan from 8,000,000 to 14,000,000. The exercise price of stock options under the 2010 Stock Plan is determined by the compensation committee of the Board of Directors, and may be equal to or greater than the fair market value of the Company’s common stock on the date the option is granted. There is no limit on the number or the value of the shares with respect to which stock options and stock appreciation rights may be granted to any one employee of the Company or a subsidiary during any one-year period. Options become exercisable over various periods from the date of grant, and generally expire between five and ten years after the grant date. As of June 30, 2017, there were 10,654,187 options issued and outstanding under the 2010 Stock Plan.

In the event of an employee’s termination, the Company will cease to recognize compensation expense for that employee. There is no deferred compensation recorded upon initial grant date; instead, the fair value of the stock-based payment is recognized ratably over the stated vesting period.

The Company has applied fair value accounting for all stock-based payment awards since inception. The fair value of each option or warrant granted is estimated on the date of grant using the Black-Scholes option pricing model. There were no options granted during the three months ended June 30, 2017. The Black-Scholes assumptions used in the six months ended June 30, 2017 and 2016 are as follows:

	Six months ended June 30,
	2017	2016
Exercise price	$0.83 - $0.87	$1.08 - $2.66
Expected dividends	0%	0%
Expected volatility	90% - 92%	102% - 117%
Risk free interest rate	1.67% - 1.75%	1.40% - 1.57%
Expected life of option	4.2 - 4.3 years	7.0 years

The Company records stock-based compensation based upon the stated vested provisions in the related agreements. The vesting provisions for these agreements have various terms as follows:

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immediate vesting;

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half vesting immediately and remaining over three years;

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quarterly over three years;

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annually over three years;

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one-third immediate vesting and remaining annually over two years;

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one half immediate vesting and remaining over nine months;

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one quarter immediate vesting and remaining over three years;

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one quarter immediate vesting and remaining over 33 months; and

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monthly over three years.

During the six months ended June 30, 2017, the Company granted 543,927 options to employees having an approximate fair value of $308,000 based upon the Black-Scholes option pricing model. During the same period in 2016, the Company granted 560,000 options to employees having an approximate fair value of $962,000 based upon the Black-Scholes option pricing model.

A summary of stock option activities for the six months ended June 30, 2017, and for the year ended December 31, 2016, is as follows:

			Weighted		Weighted Average	Aggregate
			Average Exercise		Remaining	Intrinsic
	Options		Price		Contractual Life	Value

Balance - December 31, 2015		8,941,930	$	2.14	5.67 years	$	2,900,000

Granted		3,861,425		0.98
Exercised		(445,334)		1.83		$	137,488
Expired		(338,529)		1.96
Forfeited		(383,265)		2.26

Balance - December 31, 2016		11,636,227		1.77	5.49 years	$	194,355

Granted		543,927		0.85
Exercised		(418,773)		0.40		$	163,050
Expired		(271,866)		1.84
Forfeited		(91,404)		2.00

Balance - June 30, 2017 - outstanding		11,398,111	$	1.77	5.46 years	$	8,733

Balance - June 30, 2017 - exercisable		6,798,003	$	2.06	4.78 years	$	8,733

Grant date fair value of options granted - June 30, 2017			$	308,000

Weighted average grant date fair value - June 30, 2017			$	0.57

Grant date fair value of options granted - December 31, 2016			$	3,091,000

Stock-based compensation expense included in general and administrative expenses and research and development expenses related to stock options issued to employees and consultants for the three months ended June 30, 2017 and 2016 was $870,000 and $907,000 respectively, and $2,006,000 and $1,959,000 for the six month periods ended June 30, 2017 and 2016, respectively.

As of June 30, 2017, total unrecognized stock-based compensation expense related to stock options was $4.6 million, which is expected to be expensed through February 2020.