The following table sets forth the computation of basic and diluted net income per common unit (in millions, except per unit data):



	Year Ended December 31,
	2016			2015			2014
Basic Net Income per Common Unit
Net income attributable to PAA	$	726		$	903		$	1,384
Distributions to Series A preferred units ⁽¹⁾	(122		)	—			—
Distributions to general partner ⁽¹⁾	(412		)	(608		)	(502		)
Distributions to participating securities ⁽¹⁾	(4		)	(6		)	(6		)
Undistributed loss allocated to general partner ⁽¹⁾	14			16			2
Other	(2		)	—			—
Net income allocated to common unitholders in accordance with application of the two-class method	$	200		$	305		$	878

Basic weighted average common units outstanding ⁽²⁾	464			394			367

Basic net income per common unit	$	0.43		$	0.78		$	2.39

Diluted Net Income per Common Unit
Net income attributable to PAA	$	726		$	903		$	1,384
Distributions to Series A preferred units ⁽¹⁾	(122		)	—			—
Distributions to general partner ⁽¹⁾	(412		)	(608		)	(502		)
Distributions to participating securities ⁽¹⁾	(4		)	(6		)	(6		)
Undistributed loss allocated to general partner ⁽¹⁾	14			16			2
Other	(2		)	—			—
Net income allocated to common unitholders in accordance with application of the two-class method	$	200		$	305		$	878

Basic weighted average common units outstanding ⁽²⁾	464			394			367
Effect of dilutive securities: Weighted average LTIP units	2			2			2
Diluted weighted average common units outstanding	466			396			369

Diluted net income per common unit	$	0.43		$	0.77		$	2.38

⁽¹⁾

We calculate net income allocated to common unitholders based on the distributions pertaining to the current period’s net income. After adjusting for the appropriate period’s distributions, the remaining undistributed earnings or excess distributions over earnings (“undistributed loss”), if any, are allocated to the general partner, common unitholders and participating securities in accordance with the contractual terms of our partnership agreement in effect for the period and as further prescribed under the two-class method.


⁽²⁾	We have considered the common units issued in connection with the Simplification Transactions to be outstanding for the entire fourth quarter of 2016 in the calculation of weighted average common units outstanding to more closely reflect the ownership interests in us with rights to the distributions for the periods included in the calculation of net income allocated to common unitholders.