AMAG, Citi Trends, Knight Capital, Nexstar: 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.

AMAG Pharmaceuticals Inc. (AMAG US) fell 14 percent, the most since October to $16.31. The Lexington, Massachusetts-based biopharmaceutical company agreed to buy Allos Therapeutics Inc. (ALTH US) in a stock deal valued at $686 million. Allos declined 5.8 percent to $1.94.

Apple Inc. (AAPL US) rallied 2.7 percent to $386.90, its highest price since going public in 1982. The maker of iPads, iPhones and Macintosh computers reported third-quarter profit that topped Wall Street estimates, lifted by record sales of iPhones and iPad tablets.

Bank of America Corp. (BAC US) rose the most in the Dow Jones Industrial Average, climbing 2.9 percent to $9.85. The largest U.S. lender by assets offered “considerable value” to investors as the stock traded at a 25 percent discount to its $12.65 tangible book value, Citigroup Inc. said in a note.

BigBand Networks (BBND US) increased 9.2 percent, the most since March 2009, to $2.25. The maker of digital video equipment said AT&T Inc. (T US) will use its media services platform and become a “material” customer in the second half of 2011.

Boeing Co. (BA US) had the second-biggest gain in the Dow Jones Industrial Average, climbing 2.2 percent to $72.07. The U.S. airplane maker and Airbus SAS won the industry’s biggest-ever order from AMR Corp. (AMR US).

United Technologies Corp. (UTX US) fell 1.8 percent to $87.22 for the biggest drop in the Dow. The company’s Pratt & Whitney jet engine unit lost out to a joint venture of General Electric Co. (GE US) and Safran SA (SAF FP) on the Boeing portion of the order.

Cintas Corp. (CTAS US) rose 9.8 percent, the most since October 2008, to $33.89. The largest U.S. supplier of uniforms forecast said it expects to earn at least $1.97 a share in fiscal 2012. Analysts, on average, estimated profit of $1.82 before the announcement, according to a Bloomberg survey.

Citi Trends Inc. (CTRN US) fell 12 percent, the most since May 18, to $13.97. The urban apparel retailer said it had a loss of at least 60 cents a share in the second quarter. Analysts had forecast a loss of 12 cents a share at most.

Dynavax Technologies Corp. (DVAX US) fell 19 percent, the biggest decline in the Russell 2000 Index, to $2.56. The biopharmaceutical company’s Heplisav treatment for hepatitis B failed to meet its primary endpoint at eight weeks in a consistency analysis.

E*Trade Financial Corp. (ETFC US) surged 14 percent to $14.72 for the biggest gain in the Standard & Poor’s 500 Index. Citadel LLC, E*Trade’s largest shareholder, called on the online retail broker to hold a special meeting and remove two of its directors.

Fortinet Inc. (FTNT US) plunged 19 percent, the most since its initial public offering in November 2009, to $21.61. The maker of network-security systems said second-quarter billings rose 22 percent. The growth “is not enough” as investors expected an increase of more than 30 percent, JPMorgan Chase & Co. said in a note.

Hanesbrands Inc. (HBI US) fell 9.1 percent, the most since May 2009, to $30.24. The underwear and clothing maker affirmed its forecast that 2011 earnings may be as low as $2.70 a share, compared with the $2.84 average of analyst estimates.

Intuitive Surgical Inc. (ISRG US) rose 6 percent to $397.47, the highest intraday price since the company went public in June 2000. The maker of a robotic system to perform surgery announced second-quarter earnings and revenue that beat the average estimate of analysts surveyed by Bloomberg.

Knight Capital Group Inc. (KCG US) gained 9.1 percent, the most since April 2009, to $11.29. The broker-dealer and market making firm reported second-quarter sales that beat the average analyst estimate by 11 percent, Bloomberg data show.

Manhattan Associates Inc. (MANH US) advanced 9.1 percent, the most since April 2010, to $37.97. The maker of software that helps businesses manage inventory boosted its full-year earnings forecast to at least $1.97 a share. That tops the average analyst estimate of $1.90 in a Bloomberg survey.

Murphy Oil Corp. (MUR US) advanced 4.6 percent, the most since Sept. 1, to $68.44. The operator of gasoline-filling stations may be in merger talks with Husky Energy Inc. (HSE CN), the DealReporter said, citing people familiar with the matter.

Nalco Holding Co. (NLC US) surged 24 percent, the biggest gain in the Russell 1000 Index, to $35.87. Ecolab Inc. (ECL US), the largest maker of cleaning chemicals for hotels and restaurants, agreed to acquire the Naperville, Illinois-based company for $5.4 billion to add water-treatment services. Ecolab lost 7.4 percent to $51.31 for the second-biggest drop in the S&P 500.

Nexstar Broadcasting Group Inc. (NXST US) surged 26 percent, the most since August 2009, to $9.30. The Irving, Texas-based television broadcaster hired a financial adviser to start talks with potential buyers, the Wall Street Journal reported, citing people familiar with the matter.

Piper Jaffray Cos. (PJC US) climbed 14 percent, the most since Jan. 26, to $30.85. The Minneapolis-based brokerage reported second-quarter profit of 55 cents a share, beating the average analyst estimate in a Bloomberg survey.

Quepasa Corp. (QPSA US) jumped 39 percent to $9.93 for the biggest increase in the Russell 2000 Index. The social media technology company is buying Insider Guides, the owner of myYearbook for $100 million to almost double its user base.

Riverbed Technology Inc. (RVBD US) tumbled 23 percent, the most in the Russell 1000 Index, to $32.05. The computer-networking technology company reported second-quarter revenue of $170.3 million, missing the average analyst projection for $172.8 million.

Rival F5 Networks Inc. (FFIV US) fell 6.1 percent to $111.44.

Sino-Forest Corp. (SNOFF US) advanced 9.4 percent to $4.88, the highest price since July 8. The Richard Chandler Corp. said its Mandolin Fund Pte Ltd. acquired 2.44 million shares of the Chinese forestry operator yesterday, raising its stake to 11 percent.

Skullcandy Inc. (SKUL US) was unchanged $20 on the first day of trading. The maker of fashion headphones raised $188.8 million in an initial public offering after increasing the number of shares and pricing them above the marketed range. The company sold 9.44 million shares at $20 each.

Spirit AeroSystems Holdings Inc. (SPR US) rose 7.3 percent, the most since Jan. 12, to $22.07. The maker of aircraft parts said second-quarter profit was as much as 47 cents a share, exceeding the average analyst estimate of 45 cents. The company received a “buy” rating in new coverage at BB&T Capital Markets

Textron Inc. (TXT US) rose 10 percent, the most since April 22, to $24.43. The maker of Cessna planes and Bell helicopters reported earnings of 29 cents a share, beating the 24 cent average of analyst estimates.

United Rentals Inc. (URI US) gained 8 percent, the most since Oct. 20, to $24.86. The construction-equipment rental company’s second-quarter results showed that it is adding to its fleet and that pricing trends are positive, KDP Investment Advisors Inc. said.

Yahoo! Inc. (YHOO US) dropped 7.6 percent to $13.48 for the biggest retreat in the S&P 500. The most-visited U.S. Web portal reported quarterly sales that fell short of analyst forecasts, as marketers shunned its pages in favor of rival sites.

Zillow Inc. (Z US) rose 79 percent to $35.77 on the first day of trading. The Seattle-based online real estate information service sold 3.46 million shares at $20 each in an initial public offering.

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