Stock Options (Tables)

9 Months Ended

Sep. 30, 2019

The weighted average assumptions used principally in determining the fair value of options granted to employees were as follows:

A summary of option activity for the nine months ended September 30, 2019 and is presented below:

Options	Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term in Years		Aggregate Intrinsic Value
Outstanding at December 31, 2018		9,593,990		$	4.51
Granted		3,640,800			7.15
Exercised		(107,029	)		3.61
Forfeited		(296,874	)		7.38
Outstanding at September 30, 2019		12,830,887		$	5.20		7.17	$	17,431,614
Vested and expected to vest at September 30, 2019		7,421,312		$	3.68		5.94	$	17,048,757