Note 6 - Stock-based Compensation

3 Months Ended

Mar. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

Stock-based Compensation

The following table summarizes stock option activity for employees and non-employees:

	Options			Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (years)		Aggregate Intrinsic Value

Outstanding at December 31, 2015		2,200,369		$	8.52		7.8	$	15,705
Granted		10,000		$	6.68
Exercised		(6,394	)	$	1.92
Outstanding at March 31, 2016		2,203,975		$	8.53		7.6	$	4,445
Exercisable at March 31, 2016		939,661		$	4.35		5.6	$	3,657
Vested or expected to vest at March 31, 2016 (1)		2,021,309		$	8.22		7.4	$	4,355

______________________

(1) Represents the number of vested options at March 31, 2016 plus the number of unvested options expected to vest based on the unvested options outstanding at March 31, 2016.

The Company has the following shares reserved for future issuance:

	March 31,		December 31,
	2016		2015

Stock-based compensation awards		3,073,567		2,419,901
Employee Stock Purchase Plan		297,359		297,359
Total		3,370,926		2,717,260

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details