Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2018

Schedule of warrants outstanding and exercisable for purchase of common stock


	Number of Shares
	June 30,	December 31,	Weighted-Average
Description	2018	2017	Exercise Price		Expiration Date
Issued in May 2013 financing	—	2,700,791		$ 3.76	May 2018
Issued in May 2013 financing (pre-funded)	1,977,041	1,977,041		$ 0.08	May 2020
Issued in September 2013 financing (pre-funded)	521,997	521,997		$ 0.08	Sep 2020
Issued in February 2014 financing (pre-funded)	269,844	269,844		$ 0.08	Feb 2021
Total	2,768,882	5,469,673

Summary of warrant activity

The table below is a summary of the Company's warrant activity for the six months ended June 30, 2018:


	Number of	Weighted-Average
	Warrants	Exercise Price
Outstanding at December 31, 2017	5,469,673	$	1.90
Issued	—		—
Exercised (1)	(2,700,791)		3.76
Expired	—		—
Outstanding at June 30, 2018	2,768,882	$	0.08

(1) During the six months ended June 30, 2018, a related party exercised certain of these warrants as more fully described in Note 10.

- Definition

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

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