Diamond Foods, Mela, MEMC Electronic, Tesco: U.S. Equity Movers

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.

American Dental Partners Inc. (ADPI US) surged 79 percent, the most in the Russell 2000 Index, to $18.58. The provider of management services for dental practices agreed to be bought by JLL Partners Inc. for $19 a share.

Amgen Inc. (AMGN US) rose 5.9 percent to $58.43 for the biggest increase in the Standard & Poor’s 500 Index. The world’s largest biotechnology company said it plans to buy back as much as $5 billion in shares.

Cameco Corp. (CCJ US) fell 6.3 percent, the most since Sept. 18, to $20.11. The world’s largest uranium producer reported third-quarter earnings excluding some items of 26 cents a share, missing the average analyst estimate by 19 percent.

Diamond Foods Inc. (DMND US) fell 16 percent to $39.09, the lowest price since June 2010. The maker of Kettle potato chips and snack nuts may drop if its proposed acquisition of Procter & Gamble’s Pringles unit falls apart, Barron’s reported. The company said last week the purchase would close later than expected.

Dish Network Corp. (DISH US) gained 5 percent, the most since Oct. 10, to $24.66. The second-largest U.S. satellite-TV provider said it will award a special dividend of $2 a share, allaying investors’ concerns the company will invest billions in a wireless network.

DreamWorks Animation SKG Inc. (DWA US) rose the most in the Russell 1000 Index, jumping 12 percent to $19.47. “Puss in Boots,” the company’s spinoff from its “Shrek” movies, was the top film at U.S. and Canadian theaters for a second week, taking in $33 million in ticket sales.

Dynegy Inc. (DYN US) sank 11 percent to $2.95, the lowest price since August 2010. The holding company of the third-largest independent U.S. power producer may file for bankruptcy tonight, the Wall Street Journal reported, citing people familiar with the matter. Dynegy declined to comment to Bloomberg News earlier on the prospect of bankruptcy.

EchoStar Corp. (SATS US) fell 4.1 percent to $25.36, the first decline in four days. The maker of television set-top boxes and satellite equipment reported a loss of 22 cents a share in the third quarter.

First Solar Inc. (FSLR US) dropped 3.7 percent to $47.74, the third-biggest decline in the S&P 500. The world’s largest maker of thin-film solar panels’s Chinese competitors, Yingli Green Energy Holding Co. and Renesola Ltd., cut forecasts for shipments and wrote down inventory.

MEMC Electronic Materials Inc. (WFR US) sank 4.1 percent to $4.98 for the second-biggest drop in the S&P 500.

Force Protection Inc. (FRPT US) rallied 31 percent to $5.50 for the third-biggest increase in the Russell 2000 Index. The maker of blast-resistant vehicles agreed to be acquired by General Dynamics (GD US) for $5.52 a share, or $360 million.

Houston Wire & Cable Co. (HWCC US) slipped 14 percent, the most since December 2008, to $11.04. The distributor of electrical wire and cable reported third-quarter profit of 28 cents a share, missing the 31-cent average analyst estimate in a Bloomberg survey.

Inhibitex Inc. (INHX US) rose 14 percent to $9.72, the highest price since November 2005. Deutsche Bank AG raised its price estimate for the biopharmaceutical company to $15 a share from $6, citing the potential sales of its INX-189 treatment for hepatitis C virus.

Mela Sciences Inc. (MELA US) jumped 11 percent, the most since Oct. 4, to $5.16. After receiving FDA approval for its tool for detecting the skin cancer melanoma, the New York-based company may rise as high as $20 over the next year, Barron’s reported, citing Needham & Co. analyst Dalton Chandler.

Omnivision Technologies Inc. (OVTI US) slid 18 percent, the most since Aug. 26, to $14.26. The primary supplier of camera sensors for the iPhone 4S cut its second-quarter sales forecast to at most $217 million from at least $255 million, citing an unexpected reduction in orders.

Quicksilver Resources Inc. (KWK US) slipped 8.8 percent to $7.69, the second-biggest drop in the Russell 1000 Index. The Fort Worth, Texas-based oil and natural gas producer cut its forecast for capital expenditures for the year to $690 million from $696 million, after reporting third-quarter adjusted earnings that fell short of analyst projections.

Tekelec (TKLC US) surged 14 percent to $11.29, the highest price since Feb. 9. A group led by Siris Capital Group LLC agreed to buy the mobile Internet services company Tekelec in a deal valued at about $780 million as the technology company posts improving sales prospects. Shareholders will get $11 a share in cash in the investment firm’s buyout, the companies said in a statement today.

Tesco Corp. (TESO US) slumped 18 percent, the biggest decline in the Russell 2000 Index, to $13.36. The Houston-based oilfield service company reported third-quarter earnings were 10 cents a share, missing the 23-cent profit estimated by analysts on average.

Vertex Pharmaceuticals Inc. (VRTX US) dropped 9.3 percent to $33.22, the lowest price since December 2010. The drugmaker was cut to “sector perform” from “outperform” at Royal Bank of Canada, citing potential competition for its hepatitis C treatment Incivek from Pharmasset Inc. (VRUS US).

Pharmasset rose 4.9 percent to $72.23. The Princeton, New Jersey-based company said its experimental PSI-7977 drug for treating hepatitis C cured all patients in a study.

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