(For more market insights, including options activity, click on ; for the Day Ahead newsletter link.reuters.com/mex49s; for the Morning News Call newsletter, link.reuters.com/nex49s) U.S. stocks fell for a third day on Thursday amid uncertainty over how soon the Federal Reserve will trim its market-friendly stimulus program. The Dow Jones industrial average was down 0.63 percent at 15,743.25, the S&P 500 was down 0.32 percent at 1,776.6 and the Nasdaq Composite was down 0.05 percent at 4,001.9.
** HILTON WORLDWIDE INC, $21.6, +8.00 pct
** BLACKSTONE GROUP LP, $28.94, -0.72 pct
Shares of Hilton, the world's largest hotel operator, rose 7 percent in their New York Stock Exchange debut on Thursday.
The shares opened at $21.30 after Blackstone raised more than $2.3 billion in the year's second-biggest IPO.
** FACEBOOK INC, $51.41, +4.11 pct
** WILLIAMS COS, $34.22, -0.35 pct
Standard & Poor's said on Wednesday Facebook will join its S&P 500 stock index after the close of trading on Dec. 20, cementing the social media network's rise into one of the biggest, most powerful U.S. companies.
Facebook will also replace Williams Cos in the S&P 100 index of large U.S. companies. Williams will remain in the S&P 500.
** CISCO SYSTEMS INC, $20.479, -1.92 pct
The world's top network equipment maker's Chief Executive John Chambers said on Thursday he is beginning to see the U.S. market recover but cited challenges in emerging market economies such as Russia and Brazil.
** GENVEC INC, $2.46, +41.38 pct
The company said the U.S. National Institutes of Health's advisory committee approved the protocol for the initiation of an early-stage trial to test the company's drug, CGF166, in patients with severe hearing loss.
The drug is being developed by a unit of Novartis AG under a research collaboration and license agreement with GenVec.
The stock was the top percentage gainer on the Nasdaq in midday trading.
** ARC GROUP WORLDWIDE INC, $24.24, +9.83 pct
The company, which makes precision components using molding technology, said it has formed a new 3D Material Technologies LLC unit. The unit will use 3D printing technology to make prototypes and customized parts.
** UNS ENERGY CORP, $58.74, +29.37 pct
Fortis Inc has reached a friendly deal to buy Arizona-focused utility UNS Energy for about $2.5 billion in cash, the Canadian power company said on Wednesday, as it looks to expand its presence in the United States.
The stock was the top percentage gainer on the New York Stock Exchange in midday trading.
** SUPERTEL HOSPITALITY INC, $3.05, -23.75 pct
The real estate investment trust said it suspended dividend payments on its outstanding preferred stock to preserve capital and improve liquidity.
** SIGMA DESIGNS INC, $4.36, -18.50 pct
The company, which makes chips for set-top boxes, reported lower-than-expected third-quarter results on Wednesday.
Needham cut its rating on the stock to "buy" from "hold", saying the falling demand in the company's business that makes chips for transferring IP content over cables or phone wires will pressure revenue till the second half of fiscal 2015. The brokerage also removed its $6 price target.
** LULULEMON ATHLETICA INC, $60.71, -11.18 pct
The Canadian yogawear chain, which appointed a new chief executive this week, said on Thursday it expects flat same-store sales in the crucial fourth quarter even as it reported third-quarter earnings that beat expectations.
** SOUTHWEST AIRLINES CO, $18.56, +3.28 pct
Bank of America Merrill Lynch raised its rating on the airline operator to "buy", according to Benzinga.com. The stock was the top percentage gainer on the S&P 500 in midday trading.
** VIOLIN MEMORY INC, $2.66, -13.64 pct
The enterprise flash storage maker's Chief Technology Officer, Jonathan Goldrick, has left the company, according to a Business Insider report. (r.reuters.com/kuh45v)
The company's stock, which has more than halved since the company went public in September, was the top percentage loser on the Nasdaq in midday trading.
** ARAMARK HOLDINGS CORP, $21.9, +9.50 pct
Shares of the food services provider rose 3 percent in their market debut, valuing the company at about $4.75 billion.
** CORCEPT THERAPEUTICS INC, $2.52, +12.00 pct
The company, which makes cortisol-based drugs, said it plans to start developing its lead drug, mifepristone, as a treatment for breast cancer.
Mifepristone is currently marketed as Korlym to control hyperglycemia associated with Cushing's syndrome, a rare endocrine disorder.
** NORTHWEST BIOTHERAPEUTICS INC, $3.326, -15.80 pct
The biotechnology company said it reached the number of 'events' required to trigger the first interim analysis of its late-stage trial in Glioblastoma multiforme (GBM) brain cancer patients. These events are defined as either a tumor recurrence or a death, the company said.
** ZALE CORP, $14.8, +16.08 pct
Northcoast Research upgraded its rating on the mid-tier jeweler's stock to "buy" from "neutral," according to Theflyonthewall.com.
** CIENA CORP, $21.21, -7.38 pct
The network equipment maker reported a lower-than-expected quarterly profit as costs rose 20 percent and forecast current-quarter revenue largely below Wall Street estimates.
** KINDRED BIOSCIENCES, $16.85, -5.71 pct
Shares of the clinical-stage animal biotech firm, which is in the process of developing multiple pet therapeutics, rose in their market debut, valuing the company at $130 million.
Kindred is an early clinical-stage pet biotech firm dedicated to the development and commercialization of products designed to improve pet health.
** BRIDGEPOINT EDUCATION INC, $16.85, -5.71 pct
The university operator said a tender offer by the company to purchase up to 10.3 million shares for $19.50 per share expired on Wednesday. "Because the offer was oversubscribed, the number of shares that Bridgepoint will purchase from each tendering stockholder will be prorated," the company said.
** GRAY TELEVISION INC, $12.89, +7.15 pct
Brokerage Barrington Research re-established coverage on the broadcaster's stock with an "outperform" rating. It said Gray is an "outstanding operator" and it ranks first in its local market rankings, particularly in local news.
** PROGRESS SOFTWARE CORP, $24.27, -5.20 pct
JMP Securities downgraded the enterprise software maker's stock to "market perform" from "outperform" citing concerns over the long-term prospects of the company's main software product, OpenEdge.
** SYNCHRONOSS TECHNOLOGIES INC, $30.09, +6.82 pct
Raymond James upgraded the company's stock to "strong buy" from "outperform", according to theflyonthewall.com.
Synchronoss provides software and services to communication service providers and cable operators to manage subscribers.
** IAMGOLD CORP, $3.453, -10.08 pct
The Canadian gold miner on Wednesday suspended dividend payments to reduce costs by $100 million in 2013 and said it would look for further cuts in 2014 due to the fall in gold prices.
** SUNEDISON INC, $11.52, -9.93 pct
The solar company on Wednesday cut it sales forecast to $905-$915 million, from $920-$930 million as it plans to keep more solar plants on its balance sheet rather than selling them.
The company, which is planning to spin off some plants and take them public next year, expects to sell about 380-405 megawatts (MW) of solar projects this year, lower than its earlier forecast of 405-435 MW.
** ATHENAHEALTH INC, $124.13, -5.14 pct
The company said it expects 2014 earnings of $0.98-$1.10 per share on sales of $725-$755 million, both of which were well below analysts' estimates.
Analysts on average are expecting a profit of $1.38 per share on revenue of $765.3 million, according to Thomson Reuters I/B/E/S.
** TAMINCO CORP, $19.4, -6.91 pct
The chemical maker said its secondary offering of 10 million shares was priced at $20 per share, a 4 percent discount to Wednesday's close.
** EXELIS INC, $18.67, +6.99 pct
The U.S. arms maker, which was spun off from ITT Corp in late 2011, on Wednesday said it would now spin off its military and government services business, creating a new independent firm with revenues of about $1.5 billion, and focusing the remaining portfolio on higher margin sectors.
** SYNTA PHARMACEUTICALS CORP, $4.88, +4.95 pct
The company said its lead experimental drug, ganetespib, showed positive interim results in advanced breast cancer patients in a mid-stage study.
"The clinical activity, which includes a complete clinical response as well as a complete radiological response, illustrates the exciting potential for ganetespib in breast cancer, and the rationale for exploring ganetespib in a broader spectrum of disease stages and combinations," trial investigator Neil Spector said in a statement.
** PROTHENA CORP, $28.99, +5.84 pct
Roche has raised it bet on medicines for the human brain by signing a deal with Ireland's Prothena worth up to $600 million to develop and commercialize a treatment for Parkinson's disease.