Loss per Common Share

3 Months Ended

Mar. 31, 2019

Earnings Per Share [Abstract]

Loss per Common Share

3. Loss per Common Share

Basic loss per common share is calculated by dividing net loss by the weighted-average number of common shares outstanding for the period. Diluted loss per common share is computed by dividing (a) net loss, less any anti-dilutive amounts recorded during the period for the change in the fair value of warrant liabilities, by (b) the weighted-average number of common shares outstanding for the period plus dilutive potential common shares as determined using the treasury stock method for options and warrants to purchase common stock.

The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted loss per common share because their inclusion would have had an anti-dilutive effect (in thousands):

	Three months ended March 31,
	2019		2018
Warrants to purchase shares of common stock		218		5,218
Convertible preferred stock		16,331		6,331
Options to purchase shares of common stock		4,005		3,288
Outstanding securities not included in    calculations		20,554		14,837