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US STOCKS-Futures dip ahead of data amid Fed uncertainty

* Facebook to join S&P 500

* Lululemon shares plunge in premarket after results

* Hilton Worldwide raises over $2.3 bln in record hotel IPO

* Futures down: Dow 34 pts, S&P 2.2 pts, Nasdaq 3.25 pts

NEW YORK, Dec 12 (Reuters) - U.S. stock index futures dipped on Thursday, setting Wall Street up for a third day of losses, as investors awaited a batch of economic data that may provide clues on how soon the Federal Reserve will start trimming back its stimulus efforts.

* U.S. weekly jobless claims numbers for the week ended Dec. 7 and U.S. retail sales data for November will both be released at 8:30 a.m. EST (1330 GMT).

* U.S. stocks posted their largest drop in a month Wednesday as traders took profit after a provisional budget deal out of Washington removed one of the near-term reasons for the Fed to keep up its current pace of economic stimulus. The central bank's massive bond-buying program has helped prop up the equity market for much of the year.

* Standard & Poor's said late Wednesday Facebook Inc will join its S&P 500 benchmark 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. The stock rose nearly 4 percent in premarket trading.

* Shares of Lululemon Athletica Inc fell 12.2 percent in premarket trading after the company gave a weaker-than-expected outlook.

* Hotel operator Hilton Worldwide Inc raised $2.34 billion in its IPO on Wednesday, returning to the public markets some six years after Blackstone Group LP took it private in one of the largest deals of the leveraged buyout boom.

* S&P 500 futures fell 2.2 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures fell 34 points and Nasdaq 100 futures lost 3.25 points.

* Worries over the possibility of the U.S. Federal Reserve reducing its stimulus efforts sooner than expected weighed on global equities, including European shares which slipped to a two-month low on Thursday.

* Samsung Electronics Co Ltd on Thursday lost its bid to ban sales of Apple Inc's older iPhone and iPad in South Korea after a court dismissed a lawsuit claiming the U.S. firm had infringed on three of Samsung's mobile patents.