2. NET LOSS PER SHARE

Net loss per share

Basic net loss per share is calculated using the weighted-average number of common shares outstanding during the period. Net loss per share, assuming dilution, is calculated using the weighted-average number of common shares outstanding and the dilutive effect of all potentially dilutive securities, including common stock equivalents and convertible securities. Net loss per share, assuming dilution, is equal to basic net loss per share because the effect of dilutive securities outstanding during the period, including options and warrants computed using the treasury stock method, is anti-dilutive.

The components of basic and diluted net loss per share were as follows (in thousands, except loss per share data):

Components of Basic and Diluted Net Loss Per Share

For the three and nine months ended September 30, 2021 and 2020, we excluded the following securities from net loss per share as the effect of including them would have been anti-dilutive: outstanding options exercisable into a total of 1,712,000 and 3,906,000 shares of common stock, respectively, and 2,553,000 and 2,001,000 nonvested restricted and performance stock units, respectively.