Warrants

12 Months Ended

Dec. 31, 2019

Warrants

6. Warrants

Warrant activity is summarized as follows:

Outstanding at December 31, 2017	13,229,778
Issued	290
Exercised	(2,583,042	)
Canceled	—
Outstanding at December 31, 2018	10,647,026
Issued	2,622,154
Exercised	(730,976	)
Canceled	—
Outstanding at December 31, 2019	12,538,204

The following table summarizes information with regard to outstanding warrants issued in connection with equity and debt financings and consultants as of December 31, 2019.

Issued in Connection With	Number Issued		Exercise Price		Exercisable Date		Expiration Date
February 12, 2009 Series B-1 Transaction $3.00 Investor Warrants — Class B		1,200,000	$	3.00		February 12, 2009		February 12, 2024
May 13, 2009 Series B-2 Transaction $3.00 Investor Warrants — Class B		600,000	$	3.00		May 13, 2009		May 13, 2024
June 30, 2009 Series B-2 Transaction $3.00 Investor Warrants — Class B		333,333	$	3.00		June 30, 2009		June 30, 2024
August 12, 2009 Series B-2 Transaction $3.00 Investor Warrants — Class B		200,000	$	3.00		August 12, 2009		August 12, 2024
September 30, 2009 Series B-2 Transaction $3.00 Investor Warrants — Class B		216,666	$	3.00		September 30, 2009		September 30, 2024
November 4, 2009 Series B-2 Transaction $3.00 Investor Warrants — Class B		106,666	$	3.00		November 4, 2009		November 4, 2024
December 8, 2009 Series B-2 Transaction $3.00 Investor Warrants — Class B		133,143	$	3.00		December 8, 2009		December 8, 2024
January 29, 2010 Series B-2 Transaction $3.00 Investor Warrants — Class B		216,667	$	3.00		January 29, 2010		January 29, 2025
March 8, 2010 Series B-2 Transaction $3.00 Investor Warrants — Class B		223,334	$	3.00		March 8, 2010		March 8, 2025
April 30, 2010 Series B-2 Transaction $3.00 Investor Warrants — Class B		204,192	$	3.00		April 30, 2010		April 30, 2025
May 10, 2010 Series B-2 Transaction $3.00 Investor Warrants — Class B		143,166	$	3.00		May 10, 2010		May 10, 2025
November 25, 2015 Offering Warrants		1,180,240	$	2.50		May 25, 2016		May 25, 2021
September 22, 2016 Series B-3 Transaction $3.00 Investor Warrants		698,158	$	3.00		September 22, 2016		September 22, 2023
September 29, 2016 Series B-3 Transaction $3.00 Investor Warrants		846,100	$	3.00		September 29, 2016		September 29, 2023
December 22, 2016 Private placement warrants		1,466,204	$	5.00		December 22, 2016		December 23, 2023
December 23, 2016 Series B-3 Transaction $3.00 Investor Warrants		924,780	$	3.00		December 23, 2016		December 23, 2023
December 28, 2016 Private placement warrants		644,468	$	5.00		December 28, 2016		December 28, 2023
February 27, 2017 Private placement warrants		76,776	$	5.00		February 27, 2017		February 27, 2024
2018 and 2017 Warrants issued for services		2,157	$	5.00		Various dates in 2018 and 2017		Various dates in 2025 and 2024
December 19, 2017 Line of credit warrants		500,000	$	5.00		December 19, 2017		December 19, 2024
May 23, 2019 Rights offering warrants		2,622,154	$	7.00		May 23, 2019		May 23, 2026
Total outstanding warrants		12,538,204