Warrants

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Warrants

11. Warrants

The following common stock warrants were outstanding at December 31, 2020:

	Number of Common Stock Warrants		Per Share Exercise Price		Issuance Date	Expiration Date
Replacement warrants		155	$	483.00	March 3, 2012	March 3, 2022
Issued with redeemable preferred stock*		1,420		3.50	August 16, 2017	August 16, 2022
Issued with common units in the 2018 Unit Offering		3,300		2.7568	October 2, 2018	October 2, 2023
Issued with common units in the 2018 Registered Direct Offering		92,300		5.40	October 10, 2018	October 10, 2023
Issued with common units in the 2019 Registered Direct Offering (see Note 10)		50,000		3.21	March 12, 2019	March 12, 2024
Issued with common units in the 2020 Public Offering (see Note 10)		1,630,436		0.0001	July 16, 2020		—
Total		1,777,611
*Liability classified warrants

The following common stock warrants were outstanding at December 31, 2019:

	Number of Common Stock Warrants		Per Share Exercise Price		Issuance Date	Expiration Date
Replacement warrants		155	$	483.00	March 3, 2012	March 3, 2022
Issued with redeemable preferred stock*		62		80.10	August 16, 2017	August 16, 2022
Issued with common units in 2018 Unit Offering		2,505,250		2.7568	October 2, 2018	October 2, 2023
Underwriter warrant issued in 2018 Unit Offering		196,650		6.25	October 2, 2018	September 28, 2021
Issued with common units in the 2018 Registered Direct Offering		4,629,630		5.40	October 10, 2018	October 10, 2023
Issued with common units in the 2019 Registered Direct Offering (see Note 10)		3,052,959		3.21	March 12, 2019	March 12, 2024
Total		10,384,706
*Liability classified warrants

The following is a description of the common stock warrants issued prior to January 1, 2019:

Replacement Warrants

In May 2017, the Company issued 155 common stock warrants to replace outstanding common stock warrants in connection with the Company’s merger with PharmAthene, Inc.

Redeemable Preferred Stock Warrants

In August 2017, in connection with a redeemable preferred stock issuance, the Company granted warrants to holders of redeemable preferred stock to purchase up to 78,181 shares of the Company’s common stock. Warrants issued with the redeemable preferred stock are classified as a liability and were initially recorded at their grant date fair value, and remeasured on each subsequent balance sheet date. The warrant liability is classified as a component of other long-term liabilities. During the year ended December 31, 2019, the Company exchanged 1,550 of these warrants for a combination of common stock and cash, leaving 62 of these warrants outstanding as of December 31, 2019. During the second quarter of 2020, the 62 common stock warrants were repriced to 1,420 common stock warrants due to the At-the-Market Offering which triggered an anti-dilution provision under the warrant agreement with the Company’s holders of redeemable preferred stock.   

2018 Unit Offering

On October 2, 2018, the Company issued a combined total of 2,400,000 common units and pre-funded units in a public offering (the “2018 Unit Offering”). Each common unit in the 2018 Unit Offering was sold at a public offering price of $5.00 and consisted of one share of common stock and a warrant to purchase one share of common stock at an exercise price of $6.00. Each warrant sold in the 2018 Unit Offering was exercisable immediately and expired five years from the date of issuance. Each pre-funded unit in the 2018 Unit Offering was sold at a public offering price of $4.99 and consisted of a pre-funded warrant to purchase one share of common stock at an exercise price of $0.01 per share and a warrant to purchase one share of common stock at an exercise price of $6.00. The pre-funded warrants were immediately exercisable and were able to be exercised at any time until all of the pre-funded warrants were exercised in full. All of the pre-funded warrants were exercised prior to December 31, 2018.

The warrants issued in the 2018 Unit Offering are each subject to anti-dilution protection. Accordingly, to the extent the Company was to issue additional common stock or securities convertible into common stock at an issuance price lower than exercise price of the warrants, the exercise price of the warrants would be adjusted to the lower of (i) the issuance price or (ii) the lowest volume weighted average price of the Company’s common stock on the five trading days following the announcement of the new offering.  

In conjunction with the 2018 Unit Offering, the Company issued 196,650 warrants to the underwriter. The underwriter warrants had an exercise price per share equal to 125% of the public offering price per common unit in this offering and could be exercised on a cashless basis. As of December 30, 2020, all of the underwriter warrants were exercised in full.

2018 Registered Direct Offering

On October 10, 2018, the Company issued a combined total of 4,629,630 common units and pre-funded units to certain institutional investors in a registered direct offering (the “2018 Registered Direct Offering”). Each common unit in the 2018 Registered Direct Offering was sold at a price of $5.40 and consisted of one share of common stock and a warrant to purchase one share of common stock at an exercise price of $5.40. Each warrant sold in the 2018 Registered Direct Offering was exercisable immediately and expired five years from the date of issuance. Each pre-funded unit in the 2018 Registered Direct Offering was sold at a public offering price of $5.39 and consisted of a pre-funded warrant to purchase one share of common stock at an exercise price of $0.01 per share and a warrant to purchase one share of common stock at an exercise price of $5.40. The pre-funded warrants were immediately exercisable and were able to be exercised at any time until all of the pre-funded warrants are exercised in full. All of the pre-funded warrants were exercised prior to December 31, 2018.

The 2018 Registered Direct Offering triggered a down round adjustment to the exercise price of the warrants issued in the 2018 Unit Offering from $6.00 to $4.1798.

A summary of warrant activity is as follows:

	Year Ended December 31,
	2020			2019
Warrants outstanding, beginning		10,384,706			7,344,297
Issuances		1,631,794			3,052,959
Exercises		(10,238,889	)		(12,550	)
Warrants outstanding, ending		1,777,611			10,384,706