The top after-market NYSE gainers Tuesday were Dean Foods, Chiquita Brands International, Thompson Creek Metals, Rackspace Hosting and Kenexa Corp. The top after-market NYSE losers were Willbros Group, Sothebys, Elan Corp, Williams Partners and Exterran Holdings, Inc.

Gainers

Dean Foods Co. (DF) shares rallied 26.81 percent to $15.75 in post-market trading after raising its fiscal 2012 earnings guidance. The company expects fiscal 2012 net profit to be in a range of $1.18 to $1.28 per share, up from its prior estimate of $1.10 to $1.20 per share and above analysts' estimate of $1.16 per share.

Chiquita Brands International, Inc. (CQB) shares climbed 14.58 percent to $6.05 in post-market trading. Its second quarter net profit fell to $6 million or $0.12 cents per share from $78 million or $1.68 per share in the same period last year. Revenue declined to $833.0 million but topped Reuters' estimate of $823.2 million. The company also announced that Fernando Aguirre, who has been Chief Executive for nearly nine years, would step down and a committee would look for a replacement.

Thompson Creek Metals Company Inc. (TC) shares climbed 12.03 percent to $2.98 in post-market trading. The stock has a 52-week low of $2.47, a 52-week high of $9.50 and $447.09 million in market capitalization.

Rackspace Hosting, Inc. (RAX) shares surged 11.70 percent to $55.07 in post-market trading. The company reported the second quarter net profit of $25.13 million or $0.18 per share, up from $17.56 million or $0.13 per share in the same period last year. Revenue rose 29 percent to $318.99 million compared to analysts' estimate of $317.81 million.

Kenexa Corp. (KNXA) shares surged 9.89 percent to $29.10 in post-market trading after raising full-year earnings guidance. The company currently expects fiscal 2012 net profit to be in a range of $1.07 to $1.16 per share on revenues of $359 to $366 million, up from its prior estimation of $0.98 to $1.09 per share on revenue s of $355 to $365 million.

Losers

Willbros Group, Inc. (WG) shares slumped 8.68 percent to $6.42 in post-market trading. On continuing operations, the company reported the second quarter net loss of $4.0 million or $0.08 per share compared to net profit of $7.2 million or $0.15 per share in the same quarter last year and also fell short of Reuters' estimate of net income of $0.15 per share.

Sothebys (BID) shares plunged 7.70 percent to $28.40 in post-market trading. The company reported the second quarter net profit of $85.4 million or $1.24 per share, sharply lower from $127 million or $1.81 per share in the same period last year and also widely missed Reuters' estimate of $1.49 per share.

Elan Corp, Plc. (ELN) shares plunged 4.04 percent to $10.70 in post-market trading. The stock has a 52-week low of $8.58, a 52-week high of $15.27 and $6.60 billion in market capitalization.

Williams Partners L.P. (WPZ) shares fell 3.54 percent to $51.19 in pre-market trading. The company announced Tuesday that it intends to commence an underwritten public offering of 8,500,000 common units representing limited-partner interests.

Exterran Holdings, Inc. (EXH) shares fell 3.40 percent to $17.59 in post-market trading. The company stock climbed more than 17 percent in regular trading.