Aimco and Aimco Operating Partnership calculate basic earnings per share of common stock and basic earnings per common unit based on the weighted-average number of shares of Common Stock and common partnership units outstanding. We calculate diluted earnings per share of Common Stock and diluted earnings per unit taking into consideration dilutive shares of Common Stock and common partnership unit equivalents and dilutive convertible securities outstanding during the period.

The shares of Common Stock and common partnership units outstanding at the Separation date are reflected as outstanding for all periods prior to the Separation for purposes of determining earnings per share and per unit. Each of our executives and AIR’s executives received one unvested share of our stock and one unvested share of AIR stock at the Separation date for each unvested share they held at that date. We include AIR’s executives’ rights to receive Aimco shares upon vesting in our dilutive calculations.

Aimco's Common Stock and common partnership unit equivalents include options to purchase shares of Common Stock, which, if exercised, would result in our issuance of additional shares of Common Stock and Aimco Operating Partnership’s issuance to us of additional common partnership units equal to the number of shares of Common Stock purchased under the options. These equivalents also include unvested performance-based restricted stock awards that do not meet the definition of participating securities, which would result in an increase in the number of shares of Common Stock and common partnership units outstanding equal to the number of the shares that vest. Common partnership unit equivalents also include unvested long-term incentive partnership units. We include in the denominator securities with dilutive effect in calculating diluted earnings per share and per unit during these periods.

Aimco's time-based restricted stock awards receive non-forfeitable dividends similar to shares of common stock and common partnership units prior to vesting, and our Performance-Based LTIP I units and Performance-Based LTIP II units receive non-forfeitable distributions based on specified percentages of the distributions paid to common partnership units prior to vesting and conversion. The unvested restricted shares and units related to these awards are participating securities. We include the effect of participating securities in basic and diluted earnings per share and unit computations using the two-class method of allocating distributed and undistributed earnings when the two-class method is more dilutive than the treasury stock method. Participating securities are included in the computation of diluted earnings per share and unit for the year ended December 31, 2022, because the effect of their inclusion is dilutive. Participating securities are excluded from our computation of diluted loss per share and unit for the years ended December 31, 2021 and 2020, because the effect of their inclusion would be anti-dilutive.

Reconciliations of the numerator and denominator in the calculations of basic and diluted earnings per share and per unit for the years ended December 31, 2022, 2021 and 2020 are as follows (in thousands, except per share and per unit data):


	Years ended December 31,
	2022			2021			2020
Earnings per share
Numerator:
Net income (loss) attributable to Aimco	$	75,726		$	(5,910	)	$	(5,041	)
Net income (loss) allocated to Aimco participating securities		(1,087	)		—			—
Net income (loss) attributable to Aimco common stockholders	$	74,639		$	(5,910	)	$	(5,041	)

Denominator - shares:
Basic weighted-average common stock outstanding		149,395			149,480			148,569
Diluted share equivalents outstanding		1,439			—			—
Diluted weighted-average common stock outstanding		150,834			149,480			148,569

Earnings (loss) per share - basic	$	0.50		$	(0.04	)	$	(0.03	)
Earnings (loss) per share - diluted	$	0.49		$	(0.04	)	$	(0.03	)

Earnings per unit
Numerator:
Net income (loss) attributable to Aimco Operating Partnership	$	79,657		$	(6,207	)	$	(5,310	)
Net income (loss) allocated to Aimco Operating Partnership participating securities		(1,131	)		—			—
Net income (loss) attributable to Aimco Operating Partnership's common unit holders	$	78,526		$	(6,207	)	$	(5,310	)

Denominator - units
Basic weighted-average common partnership units outstanding		157,317			157,701			156,500
Diluted partnership unit equivalents outstanding		1,457			—			—
Diluted weighted-average common partnership units outstanding		158,774			157,701			156,500

Earnings (loss) per unit - basic	$	0.50		$	(0.04	)	$	(0.03	)
Earnings (loss) per unit - diluted	$	0.49		$	(0.04	)	$	(0.03	)