Crude oil prices gained early on Monday, after media reports cited the Algerian energy minister saying all options were possible for an output cut or freeze among members of the oil-producing cartel OPEC. That came ahead of this week's meeting of major oil-producing countries in Algeria. OPEC member countries will meet informally on the sidelines.
Globally, investors are also watching the upcoming debate between U.S. presidential candidates Hillary Clinton and Donald Trump on Monday evening. Recent polls have shown the two candidates neck-and-neck ahead of the election in November.
Financials were also under pressure before the bell, with the Financials Select Sector SPDR Fund (XLF) falling 1 percent as Deutsche Bank shares hit a record low.
U.S. economic data due on Monday include monthly new home sales.
U.S. companies posting earnings on Monday included Carnival Corporation and Cal-Maine Foods ahead of the market open. Vail Resorts also posted quarterly results before the bell.