10. Stock‑Based Compensation

2015 Stock Option Plan

In October 2015, the Company’s board of directors and stockholders approved the 2015 Stock Option and Incentive Plan, or 2015 Stock Option Plan, which became effective upon the completion of the IPO. The 2015 Stock Option Plan provides the Company with the flexibility to use various equity-based incentive and other awards as compensation tools to motivate our workforce. These tools include stock options, stock appreciation rights, restricted stock, restricted stock units, unrestricted stock, performance share awards and cash-based awards. The 2015 Stock Option Plan replaced the 2014 Plan. Any options or awards outstanding under the 2014 Stock Option Plan remained outstanding and effective. The number of shares initially reserved for issuance under the 2015 Stock Option Plan is the sum of (i) 1,311,812 shares of common stock and (ii) the number of shares under the 2014 Plan that are not needed to fulfill the Company’s obligations for awards issued under the 2014 Plan as a result of forfeiture, expiration, cancellation, termination or net issuances of awards thereunder. The number of shares of common stock that may be issued under the 2015 Stock Option Plan is also subject to increase on the first day of each fiscal year by up to 4% of the Company’s issued and outstanding shares of common stock on the immediately preceding December 31.

During the year ended December 31, 2015, the Company issued 960,275 stock options to employees and directors and 69,793 stock options to non‑employees. As of December 31, 2015, there were 1,620,479 shares available for future issuance under the 2015 Plan.

2014 Stock Option and Grant Plan

In January 2014, the Company adopted the Voyager Therapeutics, Inc. 2014 Stock Option and Grant Plan (the “2014 Plan”), under which it may grant incentive stock options, non‑qualified stock options, restricted stock awards, unrestricted stock awards, or restricted stock units to purchase up to 823,529 shares of Common Stock to employees, officers, directors and consultants of the Company.

In April 2014, the Company amended the Plan to allow for the issuance of up to 1,411,764 shares of Common Stock. In August 2014, April 2015, August 2015 and October 2015 the Company further amended the Plan to allow for the issuance of up to 2,000,000, 2,047,058, 2,669,411 and 2,998,823 shares of Common Stock, respectively. During 2014 the Company issued only restricted stock awards under the Plan and during 2015 the Company only granted stock options.

The terms of stock awards agreements, including vesting requirements, are determined by the Board of Directors and are subject to the provisions of the 2014 Plan. Restricted Stock awards granted by the Company generally vest based on each grantee’s continued service with the Company during a specified period following grant. Awards granted to employees generally vest over four years, with 25% vesting on the one year anniversary and 75% vesting ratably, on a monthly basis, over the remaining three years. Awards granted to non‑employee consultants generally vest monthly over a period of one to four years.

During the year ended December 31, 2014, the Company granted a total of 1,597,988 shares of restricted stock to employees and 110,960 shares of restricted stock to non‑employee consultants at an original issuance price of $0.04 per share.

Founder Awards

In January 2014, the Company issued 1,188,233 shares of restricted stock to its Founders at an original issuance price of $0.0425 per share. Of the total restricted shares awarded to the Founders, 835,292 shares generally vest over one to four years, based on each Founder’s continued service to the Company in varying capacity as a Scientific Advisory Board member, consultant, director, officer or employee, as set forth in each grantee’s individual restricted stock purchase agreement. The remaining 352,941 of the shares issued will begin vesting upon the achievement of certain performance objectives as well as continued service to the Company, as set forth in the agreements.

These performance conditions are tied to certain milestone events specific to the Company’s corporate goals, including but not limited to preclinical and clinical development milestones related to the Company’s product candidates. Stock‑based compensation expense associated with these performance‑based awards will be recognized when the achievement of the performance condition is considered probable, using management’s best estimates. As of December 31, 2014 and 2015, management has concluded that achievement of such performance‑based milestones was not probable. Accordingly, no stock‑based compensation expense was recorded as of December 31, 2014 and 2015 related to these awards.

2015 Employee Stock Purchase Plan

In October 2015, the Company’s board of directors and stockholders approved the 2015 Employee Stock Purchase Plan. A total of 262,362 shares of common stock were initially authorized for issuance under this plan. The 2015 Employee Stock Purchase Plan became effective upon the completion of the IPO.

Stock‑Based Compensation Expense

Total compensation cost recognized for all stock‑based compensation awards in the statements of operations and comprehensive loss is as follows:

Total compensation cost recognized for all stock‑based compensation awards in the statements of operations and comprehensive loss is as follows:Total compensation cost recognized for all stock‑based compensation awards in the statements of operations and comprehensive loss is as follows:
					Period from
					June 19, 2013
	Year Ended				(Inception) to
	December 31,				December 31,
	2015		2014		2013
	(in thousands)
Research and development	$	3,218	$	297	$	—
General and administrative		809		128		—
Total stock-compensation expense	$	4,027	$	425	$	—

Restricted Stock

A summary of the status of and changes in unvested restricted stock as of December 31, 2015, 2014, and 2013 was as follows:


		Weighted
		Average
		Grant Date
		Fair Value
	Shares	Per Share
Unvested restricted common stock as of December 31, 2013	—
Issued	2,897,181	$	0.77
Vested	(318,364)	$	0.68
Repurchased	—		—
Unvested restricted common stock as of December 31, 2014	2,578,817	$	0.77
Issued	—
Vested	(717,747)	$	0.77
Repurchased	(42,809)	$	0.68
Unvested restricted common stock as of December 31, 2015	1,818,261	$	0.76

The expense related to awards granted to employees and non‑employees was $455,000 and $2,551,000, respectively, for the year ended December 31, 2015.

As of December 31, 2015, the Company had unrecognized stock‑based compensation expense related to its unvested restricted stock awards of $32,047,000, which is expected to be recognized over the remaining weighted average vesting period of 2.35 years.

Stock Options

A summary of the status of, and changes in, stock options as of December 31, 2015 and 2014 was as follows:


		Weighted		Remaining	Aggregate
		Average		Contractual	Intrinsic
		Exercise		Life	Value
	Shares	Price		(in years)	(in thousands)
Outstanding at December 31, 2014	—
Granted	1,030,068	$	8.34
Exercised	(1,344)	$	8.39
Cancelled or forfeited	(6,107)	$	7.27
Outstanding at December 31, 2015	1,022,617	$	8.35	9.5	$	13,887
Exercisable at December 31, 2015	94,762	$	7.51	9.2	$	1,363
Vested and expected to vest at December 31, 2015	1,022,617	$	8.35	9.5	$	13,887

Using the Black‑Scholes option pricing model, the weighted average fair value of options granted to employees and directors during the year ended December 31, 2015 was $5.68. The expense related to awards granted to employees and directors was $720,000 for the year ended December 31, 2015. There were no stock options granted during the year ended December 31, 2014 or the period ended December 31, 2013.

The fair value of each option issued to employees and directors was estimated at the date of grant using the Black‑Scholes option pricing model with the following weighted‑average assumptions:


	Year Ended
	December 31, 2015
Risk-free interest rate	1.6	%
Expected dividend yield	—	%
Expected term (in years)	6.0
Expected volatility	78.6	%

Using the Black‑Scholes option pricing model, the weighted average grant date fair value of options granted to non‑employees during the year ended December 31, 2015 was $7.95. Unvested options granted to non‑employees are revalued at each measurement period until they vest. The expense related to awards granted to non‑employees was $301,000 for the year ended December 31, 2015. There were no stock options granted during the year ended December 31, 2014.

The fair value of each option issued to non‑employees was estimated at each vesting and reporting date using the Black‑Scholes option pricing model. The reporting date fair value was determined using the following weighted‑average assumptions:


	Year Ended
	December 31, 2015
Risk-free interest rate	2.0	%
Expected dividend yield	—	%
Expected term (in years)	10.0
Expected volatility	84.0	%

As of December 31, 2015, the Company had unrecognized stock‑based compensation expense related to its unvested stock options of $4,753,000 which is expected to be recognized over the remaining weighted average vesting period of 3.36 years.