U.S. stock futures were lower, taking their cues from Europe and Asia, where stocks fell more than 1%.
Investors are also gearing up for a big week on the earnings front.
Citigroup(C) reported earnings on Monday of $3.8 billion, a 30% increase that topped analysts' expectations. The stock rose 2% in premarket trading.
Goldman Sachs(GS), Bank of America(BAC) and Morgan Stanley(MS) are on tap to report results later this week. Also, tech earnings begin in earnest this week, with Yahoo(YHOO), Nokia(NOK), Google(GOOG) and Microsoft (MSFT)on deck.
In corporate news Monday, Dish(DISH) said it is bidding $25.5 billion to buy Sprint Nextel(S), countering an agreement between Sprint and Japan's Softbank. Sprint's stock price surged 15% in premarket trading.
Thermo Fisher Scientific(TMO) signed an agreement to acquire Life Technologies(LIFE) in a deal valued at $13.6 billion, plus debt.
U.S. stocks broke a four-day winning streak Friday but still logged solid gains for the week.
In U.S. economic news, the New York Fed released its monthly manufacturing survey showing that conditions for New York manufacturers improved slightly in April. The indexes for general business conditions and new orders remained positive, despite modest month-to-month declines.