Amag, Aviat, CareFusion, Netflix, Vivus: U.S. Equity Movers

Shares of the following companies had unusual moves in U.S. market trading. Stock symbols are in parentheses, and prices are as of 4 p.m. in New York.

Amag Pharmaceuticals Inc. (AMAG US) retreated 10 percent, the most since Aug. 8, to $16.65. The pharmaceutical company said it had fourth-quarter revenue of $14.3 million to $15 million, below the average analyst estimate of $16 million.

Aviat Networks Inc. (AVNW US) rose 14 percent, the most since Feb. 4, to $2.02. The maker of microwave radios that are used to connect cellphone towers with the wireless network reaffirmed its second-quarter revenue estimate of as much as $110 million, compared with the average analyst estimate for $106 million, data compiled by Bloomberg show.

CareFusion Corp. (CFN US) fell the most in the Standard & Poor’s 500 Index, erasing 8.6 percent to $23.28. The maker of products to reduce hospital infections and monitor medical safety reduced the low end of its fiscal 2012 earnings forecast to $1.75 a share as preliminary results for the second quarter missed analysts’ estimates.

Con-way Inc. (CNW US) retreated 4 percent, the most since Nov. 23, to $28.87. The U.S. trucking company was cut to “hold” from “buy” at BB&T Capital Markets.

GameStop Corp. (GME US) dropped 3.5 percent, the most since Nov. 16, to $23.99. The world’s largest video-game retailer cut its fourth-quarter and year comparable sales forecast.

Inhibitex Inc. (INHX US) soared 140 percent, the biggest gain in the Russell 2000 Index, to $23.70. Bristol-Myers Squibb Co. (BMY US) agreed to buy the Alpharetta, Georgia-based biopharmaceutical firm to boost its position in hepatitis C medicines.

Other hepatitis C drug developers also rallied. Idenix Pharmaceuticals Inc. (IDIX US) surged 37 percent to $9.66. Achillion Pharmaceuticals Inc. (ACHN US) jumped 23 percent to $9.72.

IPC The Hospitalist Co. (IPCM US) fell 33 percent, the most since it went public in January 2008, to $30.61. The provider of administrative services for doctors said it earned no more than $1.74 a share last year, less than the average analysts’ estimate of $1.77 a share.

Mako Surgical Corp. (MAKO US) rose 8 percent to $31.07, the highest price since Nov. 16. The maker of orthopedic surgery devices said it expects to sell 56 to 62 systems this year, with 11,000 to 13,000 procedures performed. William Blair & Co. said the forecast beat its expectation and is “a reflection of the strong demand for robotically assisted orthopedic procedures.”

Netflix Inc. (NFLX US) added 14 percent to $98.18, for the biggest advance in the S&P 500. The owner of the streaming and DVD-by-mail service forecast it will attract millions of subscribers within a few years to the Internet film and television service it started in the U.K. and Ireland today, taking on Amazon Inc.’s (AMZN US) Lovefilm.

Questcor Pharmaceuticals Inc. (QCOR US) jumped 8.2 percent, the most since Oct. 26, to $42.14. The drug company said its paid prescription sales were “strong” in the fourth quarter of last year and it may start a pilot selling program in rheumatology this year.

Smith Micro Software Inc. (SMSI US) gained 9.9 percent to $1.44, the highest price since Oct. 18. The communications-software provider for wireless carriers and phone makers said Sprint Nextel Corp. (S US) selected the company’s Mobile Network Director for traffic management between networks.

Theravance Inc. (THRX US) plunged 19 percent, the most since October 2008, to $16.39. Relovair, an experimental medicine that the maker of treatments for respiratory disorders and bacterial infections shares with GlaxoSmithKline Plc (GSK LN), failed to beat an existing drug in a study.

Vivus Inc. (VVUS US) rallied 15 percent to $11.65, the highest price since July 2010. The maker of experimental weight-loss pill Qnexa said U.S. regulators ordered changes to a proposed warning label for the treatment.

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