Shareholders’ equity

Common Stock

As of September 30, 2017 and December 31, 2016, we had 195,000,000 shares of common stock, $0.01 cent par value per share, authorized under our Restated Certificate of Incorporation, of which 94,513,473 shares were issued and 87,326,952 shares were outstanding at September 30, 2017; 94,437,418 shares were issued and 87,250,897 shares were outstanding at December 31, 2016.

The rights, preferences and privileges of holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of our preferred stock which are currently outstanding, including our Series A Convertible Preferred Stock, or which we may designate and issue in the future.

Stock Repurchase Program

In 2011, our Board of Directors approved a $60,000 common stock repurchase program which was expanded in 2015 to $130,000. Through September 30, 2017 we had repurchased 7,186,521 shares of common stock for an aggregate purchase price of $86,276. We have made no share repurchases since April 2015 and we have $43,724 remaining under the repurchase program authorization. The repurchase program may be expanded, suspended or discontinued by our Board, in its sole discretion, at any time.

Shares of common stock repurchased are recorded at cost as treasury stock and result in a reduction of shareholders’ equity in the consolidated balance sheets. From time to time, treasury shares may be reissued and we use an average cost method for determining the cost for reissued treasury shares. The difference between the cost of the shares and the reissuance price is added to or deducted from additional paid-in capital.

Preferred Stock

As of September 30, 2017 and December 31, 2016 we had 5,000,000 shares of preferred stock, $0.01 cent par value per share, authorized under our Restated Certificate of Incorporation. In 2008, we issued 160,000 shares of our Series A Convertible Preferred Stock, all of which are held by Glencore, and at September 30, 2017 and December 31, 2016, 75,299 and 75,625 shares were outstanding, respectively. The issuance of common stock under our stock incentive programs, debt exchange transactions and any stock offering that excludes Glencore participation triggers anti-dilution provisions of the preferred stock agreement and results in the automatic conversion of Series A Convertible Preferred Stock shares into shares of common stock. The conversion of preferred to common shares is 100 shares of common for each share of preferred stock. Our Series A Convertible Preferred Stock has a par value of $0.01 per share.

Our Board of Directors may issue preferred stock in one or more series and determine for each series the dividend rights, conversion rights, voting rights, redemption rights, liquidation preferences, sinking fund terms and the number of shares constituting that series, as well as the designation thereof. Depending upon the terms of preferred stock established by our Board of Directors, any or all of the preferred stock could have preference over the common stock with respect to dividends and other distributions and upon the liquidation of Century. In addition, issuance of any shares of preferred stock with voting powers may dilute the voting power of the outstanding common stock.

The Common and Preferred Stock Activity table below contains additional information about preferred stock conversions during the nine months ended September 30, 2017 and 2016.



Common and Preferred Stock Activity:	Preferred stock		Common stock
(in shares)	Series A convertible		Treasury	Outstanding
Beginning balance as of December 31, 2016	75,625		7,186,521	87,250,897
Conversion of convertible preferred stock	(326	)	—	32,619
Issuance for share-based compensation plans	—		—	43,436
Ending balance as of September 30, 2017	75,299		7,186,521	87,326,952

Beginning balance as of December 31, 2015	76,539		7,186,521	87,038,050
Conversion of convertible preferred stock	(161	)	—	16,109
Issuance for share-based compensation plans	—		—	21,428
Ending balance as of September 30, 2016	76,378		7,186,521	87,075,587