Basic and diluted earnings (loss) per share

12 Months Ended

Dec. 31, 2020

Basic and diluted earnings (loss) per share

Basic and diluted earnings (loss) per share

21. Basic and diluted earnings (loss) per share

Basic earnings (loss) per share is calculated by dividing net income (loss) attributable to Atlantic Power Corporation by the weighted average common shares outstanding during their respective periods. Shares issued and shares repurchased during the year are weighted for the portion of the year that they were outstanding. Diluted earnings (loss) per share is computed in a manner consistent with that of basic earnings (loss) per share while giving effect to all potentially dilutive common shares that were outstanding during the period. The dilutive effect of our convertible debentures is calculated using the “if-converted method.” Under the if-converted method, the debentures are assumed to be converted at the beginning of the period, and the resulting common shares are included in the denominator of the diluted earnings (loss) per share calculation for the entire period being presented. Interest expense, net of any income tax effects, would be added back to the numerator for purposes of the if-converted calculation. The outstanding equity compensation for non-vested LTIP and Transition Equity Participation Agreement notional shares are not considered outstanding for purposes of computing basic earnings (loss) per share. However, these instruments are included in the denominator, when dilutive, for purposes of computing diluted earnings (loss) per share under the treasury stock method.

The following table sets forth the diluted net income (loss) and potentially dilutive shares utilized in the per share calculation for the years ended December 31, 2020 and 2019:

Basic	2020		2019
Numerator:
Net income (loss) attributable to Atlantic Power Corporation	$	74.2	$	(42.6)
Denominator:
Weighted average basic shares outstanding		95.8		109.3
Basic earnings (loss) per share attributable to Atlantic Power Corporation	$	0.77	$	(0.39)
Diluted
Numerator:
Net income (loss) attributable to Atlantic Power Corporation		74.2		(42.6)
Add: convertible debenture interest expense		3.8		—
		78.0		(42.6)
Denominator:
Weighted average basic shares outstanding		95.8		109.3
Share-based compensation		1.7		—
Convertible debentures		27.4		—
		124.9		109.3
Diluted earnings (loss) per share attributable to Atlantic Power Corporation		0.62		(0.39)

The following table summarizes our outstanding instruments that are anti-dilutive and were not included in the computation of our diluted earnings (loss) per share:

	2020		2019
Share-based compensation		—		1.5
Convertible debentures		—		27.8
Total		—		29.3