* Boehner comments prompt selling
* Best Buy surges on report of possible buyout
* Initial jobless claims fall, retail sales up
* Dow off 0.6 pct, S&P 500 off 0.6 pct, Nasdaq off 0.7 pct
NEW YORK, Dec 13 (Reuters) - The S&P 500 ended its six-day winning streak on Thursday, retreating as worries intensified that Washington's "fiscal cliff" negotiations were dragging on with little progress.
Anxiety about the drawn-out talks between Democrats and Republicans was enough to offset encouraging data on retail sales and jobless claims on Thursday.
There is concern that tax hikes and spending cuts, set to begin in 2013 if a deal is not reached in Washington, will hurt growth. The stock market has taken the heated rhetoric in stride of late, but downbeat remarks from Republican House Speaker John Boehner prompted some selling on Thursday.
Boehner accused President Barack Obama of "slow walking" the economy off the fiscal cliff. He is scheduled to meet with Obama later on Thursday.
"There is no conviction here and Boehner's comments - as harsh as they were - were realistic," said Jason Weisberg, managing director at Seaport Securities Corp., in New York.
"The fiscal cliff is already built in. That being said, people don't like to be told the apocalypse is coming over and over and over again. The real players in this market have already closed their books."
After coming close to a 1 percent decline for the day, the S&P 500 pared losses late in the session. The index had posted six straight sessions of gains through Wednesday's close, and at one point on Wednesday, the S&P touched its highest intraday level since Oct. 22.
While the Federal Reserve's announcement on Wednesday of a new round of economic stimulus bolstered stocks, Chairman Ben Bernanke's comments that monetary policy would not be sufficient to offset the impact of the fiscal cliff weighed on sentiment.
Apple's stock, down 1.7 percent at $529.69, was among the biggest drags on the Nasdaq in Thursday's session, while International Business Machines, down 0.5 percent at $191.99, was among the biggest weights on the Dow. A U.S. jury found that Apple's iPhone infringed three patents owned by MobileMedia Ideas.
Among the day's biggest gainers, Best Buy Co shares shot up 15.9 percent to $14.12 after a report that the company's founder is expected to offer to buy the consumer electronics retailer by the end of the week.
The Dow Jones industrial average tumbled 74.73 points, or 0.56 percent, to 13,170.72 at the close. The Standard & Poor's 500 Index fell 9.03 points, or 0.63 percent, to 1,419.45. The Nasdaq Composite Index slid 21.65 points, or 0.72 percent, to end at 2,992.16.
Energy and information technology sectors were the S&P 500's weakest performers, with the S&P energy index down 0.9 percent.
In the energy sector, shares of Nabors Industries Ltd dropped 4.7 percent to $13.85 after Jefferies cut the drilling company's rating. Shares of U.S. refining company Phillips 66 lost 1.6 percent to $52.21.
The day's economic data sent some positive signals on the economy, with weekly claims for jobless benefits dropping to nearly the lowest level since February 2008, and retail sales rising in November after an October decline, improving the picture for consumer spending.
In Europe, European Union finance ministers reached agreement to make the European Central Bank the bloc's top banking supervisor, which could boost confidence in EU leaders' ability to confront the euro zone's sovereign debt crisis.
After the bell, shares of Adobe Systems Inc rose 5.8 percent to $37.60 after the maker of Photoshop and Acrobat software posted a better-than-expected fourth-quarter profit. The stock ended the regular session at $35.53, down 1.2 percent.
Volume was roughly 6.16 billion shares traded on the New York Stock Exchange, the Nasdaq and the NYSE MKT, compared with the year-to-date average daily closing volume of 6.52 billion.
Decliners outnumbered advancers on the NYSE by a ratio of about 7 to 3, and on the Nasdaq, more than five stocks fell for every three that rose.