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



	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Basic Net Income/(Loss) per Common Unit
Net income attributable to PAA	$	33		$	297		665			599
Distributions to Series A preferred unitholders ⁽¹⁾	(36		)	(33		)	(105		)	(88		)
Distributions to general partner ⁽¹⁾	—			(102		)	—			(412		)
Distributions to participating securities⁽¹⁾	(1		)	(1		)	(2		)	(3		)
Undistributed loss allocated to general partner⁽¹⁾	—			1			—			14
Other	(4		)	—			(11		)	—
Net income/(loss) allocated to common unitholders	$	(8	)	$	162		$	547		$	110

Basic weighted average common units outstanding	725			401			714			399

Basic net income/(loss) per common unit	$	(0.01	)	$	0.40		$	0.77		$	0.27

Diluted Net Income/(Loss) per Common Unit
Net income attributable to PAA	$	33		$	297		$	665		$	599
Distributions to Series A preferred unitholders ⁽¹⁾	(36		)	(33		)	(105		)	(88		)
Distributions to general partner ⁽¹⁾	—			(102		)	—			(412		)
Distributions to participating securities⁽¹⁾	(1		)	(1		)	(2		)	(3		)
Undistributed loss allocated to general partner⁽¹⁾	—			1			—			14
Other	(4		)	—			(11		)	—
Net income/(loss) allocated to common unitholders	$	(8	)	$	162		$	547		$	110

Basic weighted average common units outstanding	725			401			714			399
Effect of dilutive securities:
LTIP units	—			1			1			1
Diluted weighted average common units outstanding	725			402			715			400

Diluted net income/(loss) per common unit	$	(0.01	)	$	0.40		$	0.76		$	0.27

⁽¹⁾

We calculate net income/(loss) 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. The Simplification Transactions, which closed on November 15, 2016, simplified our governance structure and permanently eliminated our IDRs and the economic rights associated with our 2% general partner interest. Therefore, beginning with the distribution pertaining to the fourth quarter of 2016, our general partner is no longer entitled to receive distributions or allocations on such interests.