Stock index futures pointed to a lower open on Tuesday on concerns about the state of corporate profits after several major U.S. companies reported disappointing quarterly results and even cloudier outlooks.

Caterpillar Inc shares slipped 5.4 percent to $28.85 in premarket trade after the world's No. 1 maker of building equipment posted first-quarter results and said it will suspend share repurchases.

Chemical maker DuPont Co reported a 59 percent fall in quarterly earnings, cut its full year 2009 profit forecast due to weak demand, and said it will cut costs further. Shares fell 3.3 percent to $25.86.

Bank of New York Mellon Corp said first-quarter profit fell by more than one-half as fees tumbled, and the bank slashed its dividend 63 percent in an effort to build capital. Its shares tumbles 7.3 percent to $26 in premarket trade.

We weren't expecting a great earnings period, and expectations had come down considerably, but I guess you could say not enough, said Todd Leone, head of listed trading at Cowen & Co in New York.

But for the most part we had such a tremendous move to the upside for six weeks, they had to come in very good for them to keep moving higher.

S&P 500 futures dropped 7.30 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 slid 71 points, and Nasdaq 100 futures fell 7 points.

U.S. stocks had risen for six consecutive weeks, the longest for the S&P 500 since 2007, with the Dow scoring its biggest percentage gain since 1938.

Drugmaker Merck & Co Inc , which plans to buy rival Schering-Plough Corp later this year, reported lower-than expected sales and earnings and cited the global economic slowdown. Shares dropped 3.3 percent to $24.40.

Diversified U.S. manufacturer United Technologies Corp reported a 27.8 percent fall in quarterly profit as the slumping economy crimped demand for its jet engines and air conditioners. Shares rose 1.7 percent to $46.59.

Soft drink maker Coca-Cola Co shed 1.4 percent to $43.70 after posting first-quarter results that included a 3 percent drop in revenues. [ID:nWNAB5447]. The stock fell 1.4 percent to $43.70.

At the close of trading on Friday, the blended growth rate for the first quarter, which combines actual numbers for companies that have reported earnings and estimates for companies that have yet to report, stood at negative 37.4 percent, according to Thomson Reuters data.

Shares of General Motors Corp jumped 6.6 percent to $1.77 in premarket trade after an independent oversight report on the Treasury Department's corporate rescue fund said the Obama administration will make up to $5 billion available to GM through May and will also make $500 million available to Chrysler as it seeks to reach an alliance with Fiat .

On the merger front, chipmaker Broadcom Corp said it made an unsolicited bid for storage-equipment maker Emulex Corp with an equity value of $764 million.

Broadcom shares slid 8.9 percent to $19.85, while Emulex surged 45 percent to $9.61.

Stocks slid more than 3 percent on Monday after weak results from Bank of America Corp reignited concerns over the state of the banking industry and the economy.

(Reporting by Chuck Mikolajczak; Editing by Theodore d'Afflisio and Jeffrey Benkoe)