Warrants

3 Months Ended

Mar. 31, 2019

As of March 31, 2019, the following warrants for common stock were issued and outstanding:



Issue date	Expiration date	Exercise price		Number of warrants outstanding
January 11, 2017	None	$	0.001	5,858,238
November 20, 2017	None	$	0.001	4,137,999
June 11, 2018	None	$	0.001	421,650
				10,417,887

During the three months ended March 31, 2019, 1,400,025 warrants for shares of the Company's common stock were exercised via cashless exercise, resulting in the issuance of 1,400,000 shares of common stock. During the three months ended March 31, 2018, no warrants were exercised.

Stockholders' Equity

Sale of Common Stock

In January 2019, the Company sold 1,854,838 shares of its common stock at a public offering price of $62.00 per share. After deducting underwriter discounts, commissions and offering expenses, the Company received net cash proceeds from the transaction of $107.9 million.

Share-based Compensation

Total share-based compensation expense by statement of operations classification is presented below (in thousands):



	Three Months Ended March 31,
	2019		2018
Research and development expense	$	5,157	$	1,493
General and administrative expense	5,974		2,167
	$	11,131	$	3,660

During the three months ended March 31, 2019, 235,398 shares were issued pursuant to stock option exercises, generating net proceeds of $2.7 million. During the three months ended March 31, 2018, 402,948 shares were issued pursuant to stock option exercises, generating net proceeds of $5.9 million.

Disgorgement Proceeds

In January 2019, the Company received a payment of $1.1 million representing a disgorgement of short-swing profits from the sale of common stock by a beneficial owner pursuant to Section 16(b) of the Securities Exchange Act of 1934, as amended. The Company recognized these proceeds as a capital contribution from stockholders and reflected a corresponding increase to additional paid-in capital.