Stock index futures pointed to a lower open on Tuesday as declining oil prices pressured energy shares and 3M Co's outlook for the current year came in below analysts' forecast.

3M fell 1.5 percent to $76.71 before the opening bell after the diversified manufacturer forecast 2009 earnings per share, excluding items, between $4.50 and $4.55 per share. The consensus of analysts polled by Thomson Reuters is for earnings of $4.57 a share.

Shares of McDonald's Corp slid 2.3 percent to $60.50 in premarket trading after it reported November comparable sales.

Oil prices fell below $73 a barrel, extending the previous day's 2 percent decline, hurt by the slow recovery in energy demand and ample supplies. The U.S. dollar, which has traded inversely to equities of late, firmed against a basket of currencies.

The combination of some negative corporate news, the strengthening of the dollar and the exiting of commodities is weighing on the futures pre-open, said Peter Cardillo, chief market economist at Avalon Partners in New York.

FedEx Corp could help limit losses after it said late on Monday its second-quarter earnings would easily beat its previous forecast, citing strong growth in international demand for its air services, especially in Asia and Latin America. Its shares gained 2.2 percent to $89.45.

S&P 500 futures fell 8.30 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 slipped 70 points, while Nasdaq 100 futures dipped 15.50 points.

The S&P 500 and Nasdaq ended slightly lower on Monday and the Dow was flat, reversing earlier gains following comments from Federal Reserve Chairman Ben Bernanke that sparked jitters about the pace of the economic recovery.

Investors were also watching developments in Dubai as its leaders dithered over a rescue for debt-laden company Dubai World.

General Motors Co is talking to BAIC, China's fifth-largest car maker, about a partial sale of assets associated with its Saab brand, including tooling and technology, two people with direct knowledge of the discussions said.

(Editing by Padraic Cassidy)