* Initial jobless claims on tap
* Equity markets close at 1 p.m. in holiday-shortened session
* Futures up: Dow 13 pts, S&P 1 pts, Nasdaq 3.25 pts
By Chuck Mikolajczak
NEW YORK, Dec 24 (Reuters) - U.S. stock index futures were little changed on Wednesday, after a five-day winning streak pushed the Dow and S&P 500 to new closing records and ahead of data on the labor market.
* The Dow closed above 18,000 for the first time ever and the S&P 500 ended at its 51st record of the year after an unexpectedly strong report on U.S. economic growth. The 51 new closing highs for the year are the most since 1995 and fourth most in history.
* Investors will eye weekly initial jobless claims data at 8:30 a.m. (1330 GMT) for signs of continued improvement in the labor market. Expectations call for a slight rise to 290,000 from the 289,000 in the prior week.
* Equity markets will operate on a shortened trading schedule Wednesday, closing at 1 p.m. (1800 GMT) ahead of the Christmas Day holiday on Thursday. Volume is expected to be light, which could exacerbate volatility.
* The benchmark S&P index has risen 5.5 percent in its latest rally, its best 5-day run since December 2011, fueled by a commitment by the U.S. Federal Reserve last week to take a "patient" approach toward raising interest rates and solid economic data.
* Sumitomo Mitsui Banking Corp will buy Citigroup Inc's Japanese retail banking operations in October for about 40 billion yen ($330 million), people with knowledge of the matter said.
* U.S. surgical implant maker Stryker Corp is planning a takeover offer for British medical device maker Smith & Nephew that may come within weeks, Bloomberg reported, citing people familiar with the matter. U.S.-listed shares of Smith & Nephew were down 3.5 percent to $36.70 in premarket.
* European stocks were slightly higher in a shortened session ahead of the Christmas break, gaining ground for the seventh day in a row while Asian stocks gained in the wake of the U.S. GDP report.
Futures snapshot at 7:19:
* S&P 500 e-minis were up 1 points, or 0.05 percent, with 18,536 contracts changing hands.
* Nasdaq 100 e-minis were up 3.25 points, or 0.08 percent, in volume of 3,767 contracts.
* Dow e-minis were up 13 points, or 0.07 percent, with 3,129 contracts changing hands. (Reporting by Chuck Mikolajczak; Editing by Chizu Nomiyama)