Common stock

As of March 31, 2015, the Company had authorized 100,000,000 shares of common stock, $0.0001 par value per share. Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors.

Restricted common stock

In March 2014, the Company sold 4,553,415 shares of restricted common stock to the founders of the Company ("recipients"), for $0.0004 per share, for total proceeds of $1,950. In April 2014, based upon anti-dilution provisions granted to the recipients, an additional 867,314 shares of restricted common stock were sold to the same recipients, after which the anti-dilution provisions were terminated. The restricted common stock vested 25% upon issuance, and the remaining 75% vests ratably over four years, during which time the Company has the right to repurchase the unvested shares held by a recipient if the relationship between such recipient and the Company ceases. If the relationship terminates, the Company has 90 days to repurchase unvested shares at $0.0004 per share. Such shares are not accounted for as outstanding until they vest. There were 2,456,227 shares of restricted common stock outstanding as of March 31, 2015. Unvested restricted common stock awards to non-employees are re-measured at each vest date and each financial reporting date.

The following is a summary of restricted common stock activity related to shares sold to the Company's founders:



	Number of Shares		Weighted-Average Grant Date Fair Value
Non-vested at December 31, 2014	3,218,590		$	0.10
Vested	(254,088	)	0.10
Non-vested at March 31, 2015	2,964,502		$	0.10

Early exercise of stock options

During the first quarter of 2015, 37,064 employee stock options, with a weighted-average grant date fair value of $10.79 per share, were exercised pursuant to an early exercise provision in an employee's stock option agreement. None of the exercised options had vested as of March 31, 2015, and the early exercise provision contains a repurchase option by the Company. Accordingly, the $400,000 of exercise proceeds received by the Company are being accounted for as a liability on the Company's condensed consolidated balance sheet at March 31, 2015. The proceeds received will remain classified as a liability and the related shares will not be considered outstanding, for accounting purposes, until the shares vest in the first quarter of 2016.