Basic net loss per share is determined by dividing net loss by the weighted average shares of common stock outstanding during the period, without consideration of potentially dilutive securities except for those shares that are issuable for little or no cash consideration. Diluted net loss per share is determined by dividing net loss by diluted weighted average shares outstanding. Diluted weighted average shares reflects the dilutive effect, if any, of potentially dilutive common shares, such as stock options and warrants calculated using the treasury stock method. In periods with reported net operating losses, all common stock options and warrants are generally deemed anti-dilutive such that basic net loss per share and diluted net loss per share are equal. However, in certain periods in which the exercise price of the warrants was less than the last reported sales price of Delcath’s common stock on the final trading day of the period and there is a gain recorded pursuant to the change in fair value of the warrant derivative liability, the impact of gains related to the mark-to-market adjustment of the warrants outstanding at the end of the period is reversed and the treasury stock method is used to determine diluted earnings per share.

The following potentially dilutive securities were excluded from the computation of earnings per share as of March 31, 2020 and 2019 because their effects would be anti-dilutive:

	March 31,
	2020		2019
Stock options		1,640		1,166,667
Common stock warrants - equity		1,826,599		4,202,909
Common stock warrants - liabilities		—		189,029
Common stock reserved for conversion of preferred shares		1,799,093		—
Assumed conversion of convertible notes		63,493		268,558
Total		3,690,825		5,827,163