April 21 (Reuters) - U.S. stocks opened flat on Monday as investors found few reasons to keep buying following a strong rally last week and ahead of a heavy week of corporate earnings. The Dow Jones industrial average was up 0.25 percent at 16,448.9, the S&P 500 was up 0.22 percent at 1,868.98 and the Nasdaq Composite was up 0.26 percent at 4,106.1.
** HALLIBURTON CO, $63.289, +3.92 pct
The world's No. 2 oilfield services company, reported better-than-expected quarterly results, helped by robust drilling activity in Russia, Saudi Arabia and Angola.
** HASBRO INC, $55.255, +1.18 pct
The toymaker reported a quarterly profit, compared with a year-ago loss, helped by strong demand for its toys for girls. Sales of girls' toys such as My Little Pony and Nerf Rebelle increased 21 percent to $138.7 million in the first quarter ended March 30.
** SAREPTA THERAPEUTICS INC, $36.8001, +50.82 pct
** PROSENSA HOLDING NV, $5.55, +9.47 pct
Sarepta said it would start new trials to revive the chance of approval for its experimental muscle disorder drug after the U.S. Food and Drug Administration advised the company to submit new safety and efficacy data.
Prosensa makes drisapersen, a competing drug that failed a late-stage trial in September 2012.
** TEVA PHARMACEUTICAL INDUSTRIES LTD, $51.01, +0.31 pct
** MYLAN INC, $47.94, +2.17 pct
** MOMENTA PHARMACEUTICALS INC, $11.9984, +8.09 pct
The U.S. Supreme Court on Friday denied a request by Teva to stay a lower-court ruling in a patent case that favored the developers of generic versions of the Israel-based company's top-selling multiple sclerosis drug Copaxone.
The decision could help pave the way for generic competitors of Teva's Copaxone drug to go on the market as soon as next month.
The lower-court ruling in July 2013 was in favor of two teams developing cheaper generic forms of Copaxone: one comprising Novartis AG's Sandoz Inc and Momenta Pharmaceuticals, and the other comprising Mylan Inc and Natco Pharma Ltd.
** CBEYOND INC, $9.79, +38.28 pct
Privately held enterprise Internet-based communications services provider Birch Communications Inc said it agreed to buy the data center and networking services provider Cbeyond Inc for about $323 million in cash to expand its optical fiber and data center network.
Cbeyond shareholders will get between $9.97 and $10 per share. At $9.97 per share, the offer represents a premium of 40.8 percent over the closing price of Cbeyond's stock on Thursday.
** PLUG POWER, $8.03, +9.70 pct
The US fuel cell maker said on Monday Chief Executive Andy Marsh will provide update on the company's plans for its GenKey hydrogen fuel cells, and ReliOn acquisition At 10 am ET.
** ADVANCED MICRO DEVICES INC, $4.14, +12.20 pct
The chipmaker reported better-than-expected quarterly results on Thursday and its second-quarter revenue forecast was above analysts' estimates.
At least two brokerages raised their price targets on the stock on Monday.
** CALPINE CORP, $22.28, +4.26 pct
U.S. power and energy infrastructure owner LS Power Equity Advisors LLC said it has agreed to buy about 3,500 MW of generation resources in the southeastern United States from Calpine for $1.57 billion. The portfolio consists of six combined-cycle generation facilities which use natural gas as the primary fuel source, LS Power Equity said.
Calpine mainly owns and operates natural gas-fired and geothermal power plants in North America.
** PERFECT WORLD CO LTD, $19.335, -1.20 pct
** SHANDA GAMES LTD, $6.71, +1.36 pct
China-based online game developer Perfect World said it joined the consortium offering to buy rival Shanda Games. Perfect World said it would buy 30.3 million class A Shanda Games shares for $100 million from Shanda Interactive Entertainment Ltd, a shareholder in Shanda Games.
** NU SKIN ENTERPRISES INC, $87.52, +1.27 pct
The direct-selling skincare and nutritional product company on Saturday said its Nu Skin China unit plans to immediately resume corporate-hosted business meetings and will begin accepting applications for new sales people on May 1.
"China is an important marketplace for Nu Skin and we are committed to operating in full compliance with China's direct selling regulations to promote long-term success," the company said in a statement.
** TREEHOUSE FOODS INC, $72.38, +0.32 pct
The food manufacturer said it will acquire Canada-based Protenergy Natural Foods from Whitecastle Investments Ltd, Whitecap Venture Partners and others for about C$170 million.
Protenergy Natural Foods makes private-label broth, soups and gravies.
** GENERAL MOTORS CO, $33.95, -0.09 pct
The U.S. car giant plans to invest $12 billion in China from 2014 to 2017 and build more plants next year as it competes with aggressive rivals in the world's largest auto market.
** NEWMONT MINING CORP, $25.01, +6.24 pct
The talks between Barrick Gold Corp and Newmont Mining over a combination that would create a gold mining behemoth have hit a snag, but two sources close to the situation say the companies remain keen on a deal and discussions are likely to resume.
** PFIZER INC, $30.71, +1.52 pct
The U.S. pharmaceutical giant has approached British rival AstraZeneca Plc to propose a 60 billion pound ($101 billion) takeover, Britain's Sunday Times reported.
** APPLE INC, $527.78, +0.54 pct
** GOOGLE INC, $539.44, -0.72 pct
Apple and Google are wooing game developers to ensure that top game titles arrive first on devices powered by their respective operating system, the Wall Street Journal reported, citing people familiar with the matter.
** COMCAST CORP, $49.61, +1.04 pct
** CHARTER COMMUNICATIONS INC, $121.75, +3.33 pct
Comcast is in talks with Charter Communications over selling or spinning off roughly 3 million subscribers worth approximately $18 billion to $20 billion as part of the divestitures related to its $45.3 billion takeover of Time Warner Cable, according to a source familiar with the matter.
** VIMPELCOM LTD, $9.325, +3.61 pct
Russia's Vimpelcom has resolved a long-running dispute with the Algerian government by selling it a majority stake in the country's biggest telecoms operator for $2.6 billion, while it will keep control and slash debt.
** WALT DISNEY CO, $79.49, -0.63 pct
Walt Disney Co's cable networks are expected to record high single-digit growth in operating income and domestic affiliate revenue from fiscal 2014 through 2016, Chief Financial Officer Jay Rasulo told investors on Thursday.
** SPRINT CORP, $8.57, +0.59 pct
** T-MOBILE US INC, $30.44, +0.13 pct
A possible merger between Sprint and T-Mobile could prompt U.S. regulators to rewrite rules they are now weighing for a 2015 auction of airwaves, according to sources familiar with the proposed regulations.
** LULULEMON ATHLETICA INC, $49.854, -3.59 pct
A U.S. judge has issued final dismissals of lawsuits accusing Lululemon and various company officials of defrauding shareholders by concealing defects in yoga pants.
** ATHENAHEALTH, $138.736, -4.70 pct
The healthcare IT services company on Thursday reported first-quarter adjusted earnings and revenue that fell below Wall Street estimates.
Three brokerages, including Oppenheimer, Deutsche Bank and B. Riley cut their price targets on the company' stock, citing weakness in its Epocrates business - a mobile medical application.
** SELECT COMFORT CORP, $18.98, +6.93 pct
The specialty mattress maker on Thursday reported first-quarter sales that beat analysts' estimates, helped by a 2 percent rise in comparable sales.
** WEIBO CORP, $22.65, +11.91 pct
The Chinese Twitter-like messaging service company's U.S.-listed shares were up premarket on Monday after they soared 19 percent on their debut on Thursday.
** UNITEDHEALTH GROUP INC, $76.3, +0.69 pct
The largest U.S. health insurer, said it spent more than $100 million to cover a pricey new hepatitis C drug from Gilead Sciences Inc in its first three months on the market, an amount that was "multiple" times what it had expected.
** ABBOTT LABORATORIES, $38.81, -0.31 pct
An Abbott Laboratories spinoff urged a federal appeals court to revisit a ruling in a case against GlaxoSmithKline Plc , but without disturbing landmark constitutional protections for gays and lesbians.
** KRAFT FOODS GROUP INC, $56.83, -0.14 pct
Kraft Foods is recalling about 96,000 pounds of Oscar Mayer Classic Wieners because the packages may instead contain Classic Cheese Dogs made with milk, a known allergen.
** PLATINUM UNDERWRITERS HOLDINGS LTD, $62.35, +0.31 pct
Brokerage Keefe Bruyette & Woods raised the reinsurance provider's target price to $69 from $67, after the company's earnings for the quarter ended March 31 beat analysts' estimates with strong underwriting, investing, and capital management performance. The company reported earnings per share of $2.27, higher than analysts' average estimate of $1.28, according to Thomson Reuters I/B/E/S. [ID: nPn5HRfMd]
** AMERICAN TOWER CORP, $82.44, -0.25 pct
Indian conglomerate Reliance Industries Ltd' telecommunications unit, which holds nationwide 4G permits, has agreed to lease mobile phone masts from infrastructure provider American Tower Corp's local arm, the companies said in a statement on Monday.
** CHINDEX INTERNATIONAL INC, $23.69, +3.27 pct
Chinese drugmaker Shanghai Fosun Pharmaceutical Group Co Ltd has raised its offer for U.S.-listed Chindex International Inc by 15 percent to $223.6 million after a bidding war for the China-focused hospital chain.
** PEOPLE'S UNITED FINANCIAL INC, $14.65, +0.76 pct
Brokerage Keefe Bruyette & Woods cut the lender's target price to $14.50 from $15, citing low profitability until the company improves return on assets and efficiency ratio.
** PRIVATEBANCORP INC, $29.93, +1.15 pct
KBW raised its price target on the stock to $34 from $33 after the bank reported better-than-expected first quarter results on Thursday, helped by commercial loan growth.
** LINEAR TECHNOLOGY CORP, $46.33, -0.09 pct
The analog chipmaker said on Thursday it expects revenue to grow 2-6 percent from $348 million in the third quarter, that is $355-$369 million. Analysts on average were expecting revenue of $365 million, according to Thomson Reuters I/B/E/S.
** RADIOSHACK CORP, $1.47, +4.26 pct
The struggling U.S. electronics chain is mired in talks with its lenders over its plans to close about 1,100 stores, complicating its turnaround efforts, the Wall Street Journal reported, citing sources close to the talks.
RadioShack, which operates about 4,300 stores in the United States, said in March that the plan needed permission from its lenders, adding that its credit agreements allowed it to close only about 200 stores without the approval of lead lenders, the Journal said late on Wednesday. (r.reuters.com/vyg68v)
The company reported a wider quarterly loss and a huge drop in sales during the holiday season.
** BIOGEN IDEC INC, $294.058, +1.21 pct
Biogen is pricing its newly approved long-acting hemophilia drug, Alprolix, to cost U.S. patients, and insurers, about the same per year as older, less convenient therapies whose price can reach about $300,000 annually.
The move could pressure rivals such as Pfizer Inc to lower prices for existing hemophilia treatments, which provide patients with life-saving infusions of a blood clotting agent, according to doctors and industry analysts.
** HILLSHIRE BRANDS CO, $36.14, +0.08 pct
The maker of Jimmy Dean sausages and Ball Park hot dogs said it has signed a definitive agreement to acquire Van's Natural Foods from private equity firm Catterton Partners for about $165 million to expand its presence in the frozen foods category.
Van's Natural Foods makes frozen waffles and breakfast sandwiches, as well as gluten-free cereals and crackers. (Compiled by Rohit T.K. in Bangalore; Editing by Joyjeet Das)