A summary of warrant activity during the six months ended June 30, 2020 is as follows:



Warrants outstanding, December 31, 2019	10,384,706
Warrants issued due to anti-dilution features triggered from Registered Direct Offering	1,358
Exercises	(8,235,779	)
Warrants outstanding, June 30, 2020	2,150,285

During the six months ended June 30, 2020, the Company received net proceeds of $31.3 million from warrant exercises.

For warrants classified as a liability, the following is a summary of the periodic changes in their fair value during the six months ended June 30, 2020:

Balance, December 31, 2019	$	10,000
Changes in fair value		—
Balance, June 30, 2020	$	10,000

Subsequent to the quarter ended June 30, 2020, there were additionally 1,983,110 warrants exercised resulting in net proceeds of $9.6 million and 1,630,436 pre-funded warrants issued in connection with a Public Offering (see Note 16).