Wall Street was set to open lower on Monday as investor risk aversion was revived by concerns over Greece's debt crisis and the passage of sweeping healthcare reform.

European leaders sent out conflicting signals over aid to Greece over the weekend, weighing on futures. Last week's surprise interest rate hike from India heightened worries about global fiscal tightening.

The spotlight will be on shares in the pharmaceutical, healthcare and insurance sectors after the U.S. House of Representatives approved a healthcare overhaul bill, expanding insurance coverage to nearly all Americans and handing President Barack Obama a landmark victory.

Investors could take the opportunity to lock in profits. The S&P 500 has climbed 5 percent so far this month, while the Morgan Stanley Healthcare Payor Index <.HMO> racked up its best week since early November last