U.S. stock index futures fell on Wednesday on reports of bank lending restrictions in China and as quarterly results from a host of U.S. banks increased uneasiness about the state of financial companies.

Official media and banking sources said Chinese authorities instructed some major banks to curb their lending over the rest of this month after an early burst of credit. The central bank has also told some individual lenders to increase their reserve requirement ratio by half a percentage point.

Bank of America Corp shares rose 0.2 percent to $16.35 in premarket trade after posting its fourth quarter results.

Morgan Stanley and Wells Fargo also report results on Wednesday.

Recent results from financials JPMorgan Chase & Co and Citigroup Inc revealed sizable loan losses at the banks.

The finance sector has done better than anybody else so they are starting to show signs of plateauing, said Barry Ritholtz, director of equity research at Fusion IQ in New York.

The problem with doing any sort of bank analysis is every since the mark-to-market rules were changed by the (Financial Accounting Standards Board), we don't really know what their balance sheets are.

JPMorgan has also entered exclusive talks to buy the RBS Sempra commodities joint venture, people familiar with the matter said on Wednesday, in a deal expected to be worth about $4 billion.

S&P 500 futures fell 6.8 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 lost 33 points, and Nasdaq 100 futures dropped 7.25 points.

Data on tap for Wednesday includes December U.S. producer prices, which are expected to be flat from November, according to a Reuters poll of economists. Also expected at 8:30 a.m. are December housing starts, forecast to tick up to 580,000 from the previous month, and December building permits, expected to edge higher to 590,000.

Tech shares will garner attention after IBM Corp raised its 2010 profit outlook and posted a higher-than-expected rise in fourth-quarter earnings, boosted by cost cuts and a shift to more profitable contracts.

IBM shares shed 1.5 percent to $132.10 in premarket trade.

European shares fell on Wednesday, led by miners on mounting concerns about China reining in loose monetary policy, though drugmakers gained on doubts over U.S. healthcare reform.

(Editing by Padraic Cassidy)