Shares of the following companies had unusual moves in U.S. trading. Stock symbols are in parentheses and prices are as of 4 p.m. in New York.
Alpha Natural Resources Inc. (ANR US) rose 3.9 percent to $51.83, the highest price since May 10. The Abingdon, Virginia-based coal company was picked to replace Massey Energy Co. (MEE US) in the Standard & Poor’s 500 Index, according to a statement.
American International Group Inc. (AIG US) fell 4 percent to $28.28, the lowest price since July. Losses at the insurer’s largest unit, the Chartis property-casualty business, may discourage potential buyers of the stock in future government offerings. The U.S. Treasury Department disposed of 200 million shares yesterday at $29 each. AIG sold 100 million shares.
Bridgepoint Education Inc. (BPI US) rose 12 percent, the most since May 2009, to $22.89. The for-profit provider of college classes was named best investment idea at the Ira Sohn Conference in New York.
Cabot Oil & Gas Corp. (COG US) rallied 7.1 percent to $57.25 for the biggest advance in the S&P 500. The Houston-based natural gas producer said it increased production volume from the Marcellus shale in Pennsylvania.
California Pizza Kitchen Inc. (CPKI US) jumped 11 percent, the most since April 9, to $18.47. The restaurant chain operator agreed to a $470 million offer from buyout firm Golden Gate Capital Corp., more than a year after beginning a search for a suitor.
Carter’s Inc. (CRI US) climbed 15 percent, the most since October 2003, to $32.24. Berkshire Partners LLC reported a stake equal to 13 percent in the maker of children’s clothes.
Collective Brands Inc. (PSS US) plunged 17 percent, the biggest loss in the Russell 2000 Index, to $15.31. The owner of Payless ShoeSource stores said first-quarter earnings fell short of the average analyst estimate by 48 percent as sales declined.
Dycom Industries Inc. (DY US) jumped 11 percent, the most since Nov. 23, to $15.90. The provider of contract services to phone and cable companies reported third-quarter earnings that beat analysts’ estimates and said it plans to buy back $20 million of its shares.
Express Inc. (EXPR US) dropped 12 percent, the most since its initial public offering in May 2010, to $20.12. The apparel retailer forecast second-quarter earnings won’t exceed 15 cents a share. Analysts estimated 16 cents a share on average, according to Bloomberg data.
Frontline Ltd. (FRO US) fell the second-most in the Russell 1000 Index, sliding 6.5 percent to $17.57. The world’s biggest operator of supertankers said its ships operated at a loss in the first quarter and the next three months may be no different.
Halliburton Co. (HAL US) climbed 5 percent, the most since Jan 26, to $49.87. Morgan Stanley raised its recommendation for the world’s second-largest oilfield services provider to “overweight” from “equal-weight.”
Heico Corp. (HEI US) rose 9.9 percent to $54.71, the highest price since at least July 1980. The maker of jet engine parts posted second-quarter sales and earnings that exceeded analyst forecasts, according to data compiled by Bloomberg.
Hormel Foods Corp. (HRL US) slipped 4.8 percent, the most since December 2008, to $28.59. The maker of cold cuts, Spam and Jennie-O turkey products reported second-quarter earnings of 40 cents a share, trailing the average analyst estimate by 1 cent, according to Bloomberg data.
Martha Stewart Living Omnimedia Inc. (MSO US) rallied 24 percent, the biggest gain in the Russell 2000, to $4.67. The magazine and TV show owner said it retained Blackstone Group LP to help it review proposals from parties interested in partnering or investing in the company.
National Oilwell Varco Inc. (NOV US) rose 5.7 percent, the most since Oct. 26, to $72.34. The maker of oilfield equipment may benefit from an increase in offshore rig-building, which could last through 2012 and generate up to $18 billion in revenue for the company, according to Citigroup Inc.
Polo Ralph Lauren Corp. (RL US) fell the most in the S&P 500, sinking 11 percent to $114.70. The apparel and accessory retailer reported a 36 percent decline in quarterly profit, missing analysts’ estimates, as sales growth slowed.
RF Micro Devices Inc. (RFMD US) climbed 5.7 percent to $6.08 in the biggest advance since Feb. 7. The U.S. maker of chips and radio systems for mobile phones was added to the focus list at Morgan Keegan.
Vivus Inc. (VVUS US) rose 6 percent to $8.89, the highest price since Jan. 31. The drugmaker said its avanafil drug improved erectile function in a late-stage clinical trial.
Zale Corp. (ZLC US) jumped 18 percent to $5.23, the highest price since Jan. 14. The third-largest U.S. jewelry chain reported a third-quarter loss of 44 cents a share. Analysts surveyed by Bloomberg estimated a loss of 58 cents a share.