* Boehner comments prompt selling
* Best Buy surges on report of possible buy offer
* Initial jobless claims fell sharply last week, retail sales up
* Dow off 0.7 pct, S&P 500 off 0.8 pct, Nasdaq off 0.9 pct
NEW YORK, Dec 13 (Reuters) - U.S. stocks slid after the S&P's six days of gains on Thursday as uncertainty about Washington's "fiscal cliff" negotiations offset encouraging data on retail sales and jobless claims.
Energy and information technology sectors were the S&P 500's weakest performers, with the S&P energy index down 0.9 percent.
Drawn-out fiscal negotiations between Democrats and Republicans have constrained trading. 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 overall, though, has taken it in stride.
Republican House Speaker John Boehner on Thursday accused President Barack Obama of "slow walking" the economy off the fiscal cliff.
"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."
The S&P 500 had ended higher for six straight sessions through Wednesday's close, when it touched its highest level since Oct. 22.
Apple's stock, down 2 percent at $527.69, was among the biggest drags on the Nasdaq in Thursday's session, while International Business Machines, down 0.6 percent at $192.95, was the biggest weight on the Dow.
The Dow Jones industrial average slid 92.50 points, or 0.70 percent, to 13,152.95. The Standard & Poor's 500 Index dropped 11.09 points, or 0.78 percent, to 1,417.39. The Nasdaq Composite Index fell 25.47 points, or 0.85 percent, to 2,988.34.
The latest 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.
A day after the Federal Reserve announced a new round of stimulus for the economy, markets focused on Chairman Ben Bernanke's reiteration that monetary policy would not be sufficient to offset the impact of going over the fiscal cliff.
In the energy sector, shares of Nabors Industries Ltd dropped 4.6 percent to $13.86 after Jefferies cut the drilling company's stock to "underperform" from "hold," and shares of U.S. refining company Phillips 66 lost 2.5 percent to $51.74.
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.
Best Buy Co shares shot up 15.3 percent to $14.04 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 shares hit an intraday high at $14.48 - up 18.8 percent.
CVS Caremark Corp shares gained 2 percent to $48.49 after saying it expects higher earnings in 2013.