U.S. stock index futures fell on Tuesday as strength in the dollar pressured commodity prices and investors eyed a possible pullback in equity prices after a recent run-up.

The dollar hobbled near a three-year trough against a currency basket, undermined by loose U.S. monetary policy. But analysts said the fall looked overextended due to extreme short positioning.

The dollar index <.DXY>, measured against a basket of major currencies, was last up 0.5 percent at 73.311.

Shares of mining company Freeport McMoRan Copper & Gold Inc and big metal exchange-traded funds for silver and gold, including the iShares Silver Trust and the SPDR Gold Trust , edged lower in premarket trading.

Brent crude fell 1.1 percent to $123.77 a barrel, and U.S. crude futures shed 1.2 percent to $112.32.

S&P 500 futures fell 5.8 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 dropped 54 points, and Nasdaq 100 futures lost 9.25 points.

The benchmark S&P 500 has risen 4.3 percent since April 18, when it hovered near the technical support level of 1,300.

Pfizer Inc
added 0.1 percent to $21.05 premarket after the drugmaker reported quarterly results roughly in line with expectations and said it expects to complete a review of which units to keep by the second half of the year.

Other companies expected to post earnings include Comcast Corp , MasterCard Inc , Marathon Oil Corp and Cephalon Inc .

At 10 a.m. EST, the Commerce Department releases March factory orders. Economists in a Reuters survey expected a 1.9 percent rise, compared with a 0.1 percent drop in February.

European shares slipped after a strong recent run, weighed by mining stocks on the back of lower metals prices, while Asian shares were also dragged down by miners. <.

U.S. stocks slipped Monday as an early bounce from Osama bin Laden's death gave way to questions about the longevity of the market's recent rally.

(Reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)