Stock index futures were lower on Monday as concerns about the euro zone pressured sentiment and overshadowed news of several big acquisitions.

European stocks were lower after a senior euro zone source said on Sunday that pressure was growing on Portugal to seek financial help from the European Union and International Monetary Fund. On Monday, the European Commission said no discussions were underway on an EU/IMF bailout.

Issues with European sovereign debt pressured equities throughout 2010, even as domestic data showed signs of the U.S. economy was improving.

In deal news, Duke Energy Corp agreed to buy Progress Energy Inc

. Separately, DuPont

plans to buy Danisco , a Danish food ingredient firm, for $5.8 billion.

Duke shares closed Friday at $17.79, while Progress ended at $44.72. DuPont, a Dow component, closed at $49.76.

In other deal news, a group of private equity firms, including Apollo Global Management , is interested in buying Sara Lee Corp and has approached the company, a source said. Sara Lee closed Friday at $17.43.

Investors looked ahead to Alcoa Inc , which will report quarterly results after the market closes -- the first Dow component to release results. The stock edged 0.7 percent to $16.54 in premarket trading.

JPMorgan Chase & Co and Intel Corp are slated to report later in the week.

February crude futures rallied 0.8 percent to $88.72 per barrel after the Trans Alaska Pipeline was shut due to a leak.

S&P 500 futures fell 5.9 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 42 points and Nasdaq 100 futures lost 8.25 points.

U.S. stocks fell Friday after a court ruling in a key foreclosures case prompted investors to pull out of bank stocks, adding to weakness after a lackluster jobs report. Despite the day's losses, the S&P 500 and Dow recorded a sixth straight week of advances.

(Editing by Jeffrey Benkoe)

Portugal