14. Stock incentive plan

2000 Stock Incentive Plan

Options granted under the 2000 Stock Incentive Plan were all non‑qualified stock options. As of December 31, 2014 options to purchase 50,000 shares were outstanding. The 50,000 shares remaining under the 2000 Stock Incentive Plan expired in January 2015. No shares were available for future grant under the 2000 Stock Incentive Plan.

2006 Equity Incentive Plan

As of December 31, 2015 and December 31, 2014, 7,621,127 and 8,245,761 shares were reserved for issuance under the 2006 Plan, respectively. As of December 31, 2015, 594,750 restricted shares have been issued (see Note 2 (Summary of significant accounting policies—long‑term incentive restricted stock agreement assumptions and vesting requirements)) and no options have been issued below fair value. As of December 31, 2015 and December 31, 2014, zero shares of common stock were available for future issuance under the 2006 Plan.

2012 Equity Incentive Plan

The Company’s 2012 Equity Incentive Plan, which authorizes the issuance of an aggregate of 5,000,000 shares plus (i) any shares available for issuance under the Company’s 2006 Equity Incentive Plan, which was terminated upon the effective date of the 2012 Plan, and (ii) any shares subject to outstanding options under the Company’s 2000 Stock Incentive Plan and the Company’s 2006 Equity Incentive Plan which are forfeited, cancel or which expire. As of December 31, 2015, 8,874,274 shares were reserved for future issuance and 5,121,052 were available for grants under the Company’s 2012 Equity Incentive Plan.

A summary of stock option activity for the year ended December 31, 2015 is as follows:


				Weighted-average
	Number of	Weighted-average		remaining contractual	Aggregate
	options	exercise price		life (in years)	intrinsic value
Outstanding as of December 31, 2014	7,066,876	$	2.44	5.22	$	885,057
Options granted	1,869,446		2.50
Options exercised	(946,475)		2.24
Options cancelled	(505,347)		2.70
Options expired	(50,000)		4.00
Options forfeited	(95,204)		2.97
Outstanding as of December 31, 2015	7,339,296		2.45	5.80		4,587,530
Options exercisable as of December 31, 2015	5,315,067		2.39	4.18		3,613,601
Vested and expected to vest as of December 31, 2015	7,289,098		2.44	5.50		4,566,241

The following table provides additional information pertaining to the Company’s stock options:


	Year ended December 31,
	2015		2014		2013
Weighted-average grant date fair value for options granted during the period	$	0.92	$	1.36	$	1.14
Total fair value of options vested during the period		784,965		775,899		949,588
Total intrinsic value of options exercised during the period		1,090,711		803,141		212,580

The exercise prices range from $1.20 to $3.64 for stock options outstanding and exercisable as of December 31, 2015.

The aggregate intrinsic value of stock options outstanding, vested and unvested expected to vest, and exercisable, represent the total pre‑tax intrinsic value, based on the closing prices of $3.05 and $2.08 of PLPM as reported on NASDAQ on December 31, 2015 and 2014, respectively.

The following table summarizes the status of the non‑vested shares of restricted stock grants as of December 31, 2015:


		Weighted-Average
	Number of	Grant Date Fair
	Awards	Value
Non-vested awards as of January 1, 2015	1,641,585	$	1.13
Awards granted	752,835		1.54
Awards vested	(158,467)		2.68
Awards repurchased	—		—
Awards cancelled and forfeited	(1,011,216)		0.74
Non-vested awards as of December 31, 2015	1,224,737	$	1.71

2012 Employee Stock Purchase Plan

The Company’s 2012 Employee Stock Purchase Plan authorizes the issuance of an aggregate of 800,000 shares of common stock. The number of shares of common stock reserved for issuance under the Company’s 2012 Employee Stock Purchase Plan will increase automatically on the first day of January of each of 2015 through 2019 by an amount equal to 1% of the number of shares of common stock outstanding on the preceding December 31, unless the Company’s Board of Directors elects to authorize a lesser number of shares in any given year. In January 2015 and 2016, the Board of Directors elected not to increase the shares reserved for issuance. As of December 31, 2015 no shares are issued or outstanding under the 2012 Employee Stock Purchase Plan.

Under the Company’s 2012 Employee Stock Purchase Plan, eligible employees will be able to acquire shares of our common stock by accumulating funds through payroll deductions. The purchase price for shares of our common stock purchased under the Company’s 2012 Employee Stock Purchase Plan will be 85% of the lesser of the fair market value of our common stock on (1) the first trading day of the applicable offering period and (2) the last trading day of each purchase period in the applicable offering period. The Company’s 2012 Employee Stock Purchase Plan will terminate on the tenth anniversary of the first purchase date, unless it is terminated earlier by the Company’s Board of Directors or as a result of the issuance of all of the shares of our common stock reserved for issuance under the Company’s 2012 Employee Stock Purchase Plan.