Earnings Per Share

12 Months Ended

Dec. 31, 2020

The following table is a reconciliation of the weighted-average amounts used in calculating loss per share for the years ended December 31:


(Amounts in millions)	2020	2019	2018
Basic and diluted common shares outstanding	77.8	71.1	64.3

Potential common shares issuable to employees upon exercise or conversion of shares under the Company's stock-based compensation plans and upon exercise of the Ripple Warrants (as defined below) are excluded from the computation of diluted earnings per common share when the effect would be anti-dilutive. All potential common shares are anti-dilutive in periods of net loss available to common stockholders. Stock options are anti-dilutive when the exercise price of these instruments is greater than the average market price of the Company's common stock for the period, regardless of whether the Company is in a period of net loss available to common shareholders.

The following table summarizes the weighted-average potential common shares excluded from diluted loss per common share as their effect would be anti-dilutive:


(Amounts in millions)	2020	2019	2018
Shares related to stock options	0.3	0.9	1.8
Shares related to restricted stock units	4.5	2.7	2.3
Shares related to Ripple warrants	6.0	1.4	—
Shares excluded from the computation	10.8	5.0	4.1