Stock index futures advanced sharply on Tuesday after a bullish Alcoa forecast boosted the outlook for the commodities sector, signaling a stronger global economy.

* Alcoa Inc shares rose 2.8 percent in premarket trading after it forecast revenues above expectations and a forecast a deficit for the aluminum market. [ID:nL1E8C94UU]

* Copper prices were up 2.6 percent, the best performance in a week, as markets bet on stronger economies and more demand.

* S&P 500 futures rose 13 points and were above 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 gained 107 points and Nasdaq 100 futures added 22 points.

* Investors were nonetheless cautious ahead of Spanish and Italian debt auctions later in the week, which will test appetite for the bonds of the two countries at the forefront of the euro zone debt crisis.

* U.S. bank stocks were expected to continue a rebound in which the KBW bank index is up 6.9 percent so far this year. The Select Sector Financial SPDR exchange-traded fund gained 1.2 percent in light premarket trading.

* The U.S. Securities and Exchange Commission has urged banks to publish more details about their exposure to European sovereign debt, a factor in the recent bankruptcy of the futures brokerage MF Global Holdings Ltd .

* Microsoft Corp shares added 0.6 percent premarket a day after it said sales of its Kinect sensing device for the Xbox game console hit more than 18 million since its launch.

* Oshkosh Corp said billionaire investor Carl Icahn would like to increase his stake to 20 percent from his current 10 percent ownership.

* Liz Claiborne Inc , which recently changed its name, cut its annual outlook and said the finance chief was leaving. The shares were down 10 percent in light premarket trading.

* Stocks ended slightly higher on Monday in a light-volume session as investors stayed cautious ahead of corporate earnings and key auctions for European debt this week.

(Reporting by Rodrigo Campos; editing by Jeffrey Benkoe)