Stock index futures fell on Monday on worries about the euro-zone debt crisis after Standard & Poor's cut Italy's rating outlook and Spain's ruling Socialists suffered a setback in elections.

S&P cut its rating outlook for Italy to negative from stable, citing weak growth prospects and increased risks from a mountain of debt.

The cut comes on the heels of a downgrade of Greece's credit rating by Fitch Ratings on Friday.

Adding to the worries, Spain's Socialists, reeling from losses in local elections, now face a balancing act between voter anger over sky-high unemployment and investor demands for strict austerity measures.

Removing equity exposure amid sovereign debt concerns is highlighting a headline-driven morning, said Andre Bakhos, director of market analytics at Lek Securities in New York.

We are experiencing another cycle of concerns that is causing investors to question the risk-reward scenario in equities. Until there is better visibility, investors will play their cards close to the vest.

Worries about euro-zone debt sapped demand for riskier assets and prompted investors to shift funds into U.S. government debt, gold and the dollar.

The political and economic climate in Europe sent the euro to a two-month low versus the dollar <.DXY>, which dented commodity prices in turn. U.S. crude oil futures shed 2.4 percent.

Alcoa Inc lost 1.9 percent to $15.95 and Freeport-McMoRan Copper & Gold fell 2.3 percent to $47.25.

S&P 500 futures fell 10.8 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration of the contract. Dow Jones industrial average futures tumbled 120 points while Nasdaq 100 futures fell 23.75 points.

Sony Corp <6758.T> said it expected to post a $3.2 billion net loss for the year that ended on March 31 due to a write-off on tax credits, the latest in a string of grim headlines for the consumer electronics giant. U.S.-listed shares dropped 2.7 percent to $26.31 in premarket trading.

U.S. stocks fell on Friday, also on euro zone concerns, sending the S&P to its third straight weekly decline for the first time since August 2010.

(Reporting by Chuck Mikolajczak; Editing by Kenneth Barry)