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
23 .
basic and diluted income per common share .
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 : 2168454 for outstanding warrants to purchase the company ' s stock 353960 for unvested restricted stock awards and 4919760 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 : .

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.