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.
Alleghany Corp. (Y US) fell 6.8 percent, the most since Aug. 10, to $293.01. The company agreed to buy reinsurer Transatlantic Holdings Inc. for $3.4 billion in cash and stock and said it would appoint a former Berkshire Hathaway Inc. executive as chairman of the target company.
Clearwire Corp. (CLWR US) rose 8.2 percent, the most since Nov. 2, to $1.59. The wireless carrier’s warning that it could skip a debt payment coming due on Dec. 1 may be a “ploy” to win financial support from partner Sprint Nextel Corp. (S US) or another company, said John Fruit, manager of the Nuveen High Income Bond Fund.
ELong Inc. (LONG US) rallied 10 percent to $15.41, the highest price since Oct. 21. Expedia Inc. (EXPE US) said it bought Renren Inc.’s (RENN US) stake in the Chinese online-travel company for $72.4 million. Renren retreated 8.9 percent to $3.90.
Focus Media Holding Ltd. (FMCN US) plunged 39 percent, the most since November 2008, to $15.43. Muddy Waters LLC, the short-selling firm known for prompting Sino-Forest Corp.’s retreat, recommended betting against the Shanghai-based digital advertising company.
Gilead Sciences Inc. (GILD US) slid 9.1 percent, the most in the Standard & Poor’s 500 Index, to $36.26. The world’s largest maker of HIV medicines, agreed to buy Pharmasset Inc. (VRUS US) for about $11 billion, betting that its experimental hepatitis C treatments will lead the next generation of therapies in a market that may reach $20 billion by 2020.
Pharmasset surged a record 85 percent to $134.14. Inhibitex Inc. (INHX US), which is also developing a hepatitis C treatment, soared 19 percent to $10.61.
Nvidia Corp. (NVDA US) climbed 5 percent, the biggest gain in the S&P 500, to $14.63. The maker of three-dimensional graphics processors will supply the next round of graphics processing units for Apple Inc. (AAPL US)’s MacBooks, according to SemiAccurate, which didn’t cite a source.
Regeneron Pharmaceuticals Inc. (REGN US) gained 10 percent, the most since April 27, to $55. The company won U.S. approval of Eylea, a treatment for a common cause of blindness that will rival Roche Holding AG’s (ROG VX) Lucentis.
Research In Motion Ltd. (RIMM US) fell 4.6 percent to $17.36, the lowest price since May 2004. Analysts at RBC Capital Markets and JMP Securities LLC cut profit estimates for the smartphone maker, and RIM said some customers couldn’t turn on their BlackBerry Bold devices.
Zillow Inc. (Z US) sank 13 percent, the biggest decline in the Russell 2000 Index, to $23.52. The real estate website that had its initial public offering in July “is being pressured by sales from pre-IPO investors now that a lock-up period has ended,” Justin Patterson, an analyst at Morgan Keegan & Co., said in e-mail.