Aimco and the Aimco Operating Partnership calculate basic earnings per common share 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 and diluted earnings per unit taking into consideration dilutive common stock and common partnership unit equivalents and dilutive convertible securities outstanding during the period.

Our common stock and common partnership unit equivalents include options to purchase shares of Common Stock, which, if exercised, would result in Aimco’s issuance of additional shares and the Aimco Operating Partnership’s issuance to Aimco of additional common partnership units equal to the number of shares purchased under the options. These equivalents also include unvested total shareholder return, or TSR, 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 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.

Our restricted stock awards that are subject to time-based vesting receive non-forfeitable dividends similar to shares of Common Stock and common partnership units prior to vesting, and our TSR long-term incentive partnership 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.

Reconciliations of the numerator and denominator in the calculations of basic and diluted earnings per share and per unit for the three and nine months ended September 30, 2020 and 2019, are as follows (in thousands, except per share and per unit data):

	Three Months Ended September 30,					Nine Months Ended September 30,
	2020			2019		2020		2019
Earnings per share
Numerator:
Basic and dilutive net (loss) income attributable to Aimco common stockholders	$	(25,046	)	$	2,003	$	20,845	$	332,805

Denominator – shares:
Basic weighted-average Common Stock outstanding		148,544			148,434		148,532		147,474
Dilutive share equivalents outstanding		—			202		96		218
Dilutive weighted-average Common Stock outstanding		148,544			148,636		148,628		147,692

Earnings per share – basic and diluted	$	(0.17	)	$	0.01	$	0.14	$	2.26

Non-dilutive share equivalents outstanding		9,007			—		8,337		—

Earnings per unit
Numerator:
Basic and dilutive net (loss) income attributable to the Aimco Operating Partnership's common unitholders	$	(26,387	)	$	2,138	$	21,979	$	351,594

Denominator – units
Basic weighted-average common partnership units outstanding		156,508			156,618		156,559		155,644
Dilutive partnership unit equivalents outstanding		—			261		133		327
Dilutive weighted-average common partnership units outstanding		156,508			156,879		156,692		155,971

Earnings per unit – basic and diluted	$	(0.17	)	$	0.01	$	0.14	$	2.26

Non-dilutive partnership unit equivalents outstanding		2,220			—		1,596		—

The Aimco Operating Partnership has various classes of preferred OP Units, which may be redeemed at the holders’ option. The Aimco Operating Partnership may redeem these units for cash, or at its option, shares of Common Stock. As of September 30, 2020, these preferred OP Units were potentially redeemable for approximately 2.4 million shares of Common Stock (based on the period end market price), or cash. The Aimco Operating Partnership has a redemption policy that requires cash settlement of redemption requests for the preferred OP Units, subject to limited exceptions. Accordingly, we have excluded these securities from earnings per share and unit computations for the periods presented above, and we expect to exclude them in future periods.

Dividends and distributions paid during the three and nine months ended September 30, 2020 and 2019, were as follows:

In the first quarter of 2019, the Board of Directors authorized a special dividend and special distribution of $2.02, which is included in the $2.80 in the table above. The special dividend and distribution in the first quarter of 2019 consisted of the below (in millions):

In connection with the 2019 special dividend and distribution, the Board of Directors authorized a reverse stock split during the three months ended March 31, 2019. The reverse split combined every 1.03119 common shares and common partnership units into one common share or common partnership unit and was intended to neutralize the dilutive impact of the shares and units issued in the special dividend and distribution. As a result, the number of shares and units outstanding after the dividend/distribution and reverse split was unchanged from the number outstanding immediately prior to the two actions.