Earnings per share ("EPS") is calculated using the two-class method, which allocates earnings among common stock and participating securities to calculate EPS when an entity's capital structure includes either two or more classes of common stock or common stock and participating securities. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are participating securities. As such, shares of any unvested restricted stock of the Company are considered participating securities. The dilutive effect of options and their equivalents (including non-vested stock issued under stock-based compensation plans), is computed using the "treasury" method as this measurement was determined to be more dilutive between the two available methods in each period. The Company had no dilutive common share equivalents during the year ended December 31, 2019, due to the results of operations being a loss from continuing operations, net of tax. The following potential weighted common shares were excluded from diluted EPS for the year ended December 31, 2018 as the shares were antidilutive: 2,168,454 for outstanding warrants to purchase the Company's stock, 353,960 for unvested restricted stock awards, and 4,919,760 for convertible preferred stock. The following table presents a reconciliation of net income (loss) used in basic and diluted EPS calculations (in millions, except per share amounts):

Years Ended December 31,	Years Ended December 31,

2019	2018

Net (loss) income attributable to common stock and participating preferred stockholders	$(31.5)	$155.6

Earnings allocable to common shares:

Numerator for basic and diluted earnings per share

Participating shares at end of period:

Weighted-average common stock outstanding	44.8	44.3

Unvested restricted stock	0.6	0.4

Preferred stock (as-converted basis)	2.1	4.9

Total	47.5	49.6

Percentage of loss allocated to:

Common stock	94.3 %	89.3 %

Unvested restricted stock	1.3 %	0.8 %

Preferred stock	4.4 %	9.9 %

Net (loss) income attributable to common stock, basic	$(29.7)	$139.0

Distributed and Undistributed earnings to Common Shareholders:

Effect of assumed shares under treasury stock method for stock options and restricted shares and if-converted method for convertible instruments	—	(3.3)

Income from the dilutive impact of subsidiary securities	—	—

Net (loss) income attributable to common stock, diluted	$ (29.7)	$ 135.7

Denominator for basic and dilutive earnings per share

Weighted average common shares outstanding - basic	44.8	44.3

Effect of assumed shares under treasury stock method for stock options and restricted shares and if-converted method for convertible instruments	—	2.5

Weighted average common shares outstanding - diluted	44.8	46.8

Net (loss) income attributable to participating security holders - Basic	$ (0.66)	$ 3.14

Net (loss) income attributable to participating security holders - Diluted	$ (0.66)	$ 2.90

Question: How is Earning Per Share (EPS) calculated?
Answer: calculated using the two-class method, which allocates earnings among common stock and participating securities to calculate EPS when an entity's capital structure includes either two or more classes of common stock or common stock and participating securities.