Stock index futures fell on Thursday as investors awaited data to assess the impact of rising commodity prices amid growing concerns over Chinese inflation.

Risk appetite retreated on fears of monetary tightening in China after a media report suggested the country's inflation figures will be higher than expected in March.

Some caution was also expected before corporate results, with the spotlight likely to be on the possible impact of rising raw material costs on margins and the effect of supply chain disruptions arising from the earthquake in Japan.

Google is scheduled to release results after markets close on Thursday, with analysts expecting to see a 25 percent year-on-year increase in net revenue to $6.32 billion and earnings per share of $8.10, up from $6.76 a year earlier.

Investors will be closely eyeing the producer price index figures for March due at 8:30 a.m. (1230 GMT). Year-on-year producer prices are forecast to rise to 6.2 percent from 5.6 percent.

Other data include weekly jobless claims numbers at 8:30 a.m. Economists in a Reuters survey expect jobless claims fell to 380,000 from 382,000 last week.

Commodities trader Glencore outlined its initial public offering of up to $12 billion, including plans for a May debut that will boost its firepower for acquisitions and make paper millionaires of its partners.

U.S. regulators are probing whether some major banks colluded to manipulate a global benchmark interest rate before and during the financial crisis, the Wall Street Journal reported, citing people familiar with the situation.

In a frenzy to protect its interests at the start of the credit crisis, Goldman Sachs Group Inc sold mortgage-linked derivatives to clients at inflated prices and misrepresented the nature of the deals, according to documents released by a Senate subcommittee.

In other company news, Italian car maker Fiat wants to hike its stake in Chrysler to 46 percent by June, as soon as the U.S. group manages to repay $7 billion of government debt, an Italian daily said.

Suppliers to Apple Inc have begun production of white iPhones after a delay of almost 10 months, pointing to a launch date of within a month, two people familiar with the situation said on Thursday.

S&P 500 futures fell 7 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 49 points and Nasdaq 100 futures lost 16.50 points.

U.S. stocks finished mostly flat in a choppy session on Wednesday as investors bet on strong technology earnings even as JPMorgan Chase's numbers weighed on other market sectors.

(Reporting by Angela Moon, Editing by Kenneth Barry)