Capital Structure

On August 17, 2017, we entered into the Merger Agreement with Volt Parent, LP (“Volt Parent”) and Volt Merger Sub, Inc. (“Merger Sub”), a wholly-owned subsidiary of Volt Parent, pursuant to which Merger Sub merged with and into Calpine, with Calpine surviving the Merger as a subsidiary of Volt Parent. On March 8, 2018, we completed the Merger contemplated in the Merger Agreement.

At the effective time of the Merger, each share of Calpine common stock outstanding as of immediately prior to the effective time of the Merger (excluding certain shares as described in the Merger Agreement) ceased to be outstanding and was converted into the right to receive $15.25 per share in cash or approximately $5.6 billion in total. Also at the effective time of the Merger, the common stock of Merger Sub became the new common stock of Calpine Corporation. See Notes 2 and 13 for a discussion of the Merger and treatment of the outstanding share-based awards to employees at the effective time of the Merger, respectively.

Common Stock

Our authorized common stock consists of 5,000 shares and 1.4 billion shares of Calpine Corporation common stock as of December 31, 2018 and 2017, respectively. Common stock issued as of December 31, 2018 and 2017, was 105.2 shares and 361,677,891 shares, respectively, at a par value of $0.001 per share. Common stock outstanding as of December 31, 2018 and 2017, was 105.2 shares and 360,516,091 shares, respectively. The table below summarizes our common stock activity for the years ended December 31, 2018, 2017 and 2016.



	Shares Issued		Shares Held in Treasury		Shares Outstanding
Balance, December 31, 2015	356,755,747		(93,743	)	356,662,004
Shares issued under Calpine Equity Incentive Plans	2,871,366		(449,079	)	2,422,287
Share repurchase program	—		(22,527	)	(22,527	)
Balance, December 31, 2016	359,627,113		(565,349	)	359,061,764
Shares issued under Calpine Equity Incentive Plans	2,050,778		(596,451	)	1,454,327
Balance, December 31, 2017	361,677,891		(1,161,800	)	360,516,091
Shares issued under Calpine Equity Incentive Plans	355,805		(477,711	)	(121,906	)
Cancellation of Calpine Corporation common stock in accordance with the Merger Agreement	(362,033,696	)	1,639,511		(360,394,185	)
Conversion of Merger Sub common stock to Calpine Corporation common stock in accordance with the Merger Agreement	105.2		—		105.2
Balance, December 31, 2018	105.2		—		105.2

Treasury Stock

As of December 31, 2018 and 2017, we had treasury stock of nil shares and 1,161,800 shares, respectively, with a cost of nil and $15 million, respectively. Our treasury stock consists of shares repurchased as well as our common stock withheld to satisfy federal, state and local income tax withholding requirements for vested employee restricted stock awards and net share employee stock options exercises under the Equity Plan. All treasury stock was held at cost and retired at the effective time of the Merger in accordance with the Merger Agreement.