Dec 4 (Reuters) - U.S. equity index futures fell on Sunday after Italy's Prime Minister Matteo Renzi was projected to have lost a referendum on constitutional reform by a wide margin.
Such a result would throw his future into doubt and open the door to renewed political instability in Italy.
S&P 500 e-mini futures were down 0.5 percent shortly after electronic trading resumed on Sunday evening, signaling Wall Street could start the week on a shakier footing after stumbling last week for the first time since the U.S. election.
Last week, the S&P 500 shed 1 percent. Major Wall Street indexes had previously hit a series of record highs over the past three weeks in the wake of Donald Trump's victory in the U.S. presidential election, as investors have rotated into sectors expected to benefit from campaign promises of tax cuts, infrastructure spending and bank deregulation. (Reporting by Jessica Resnick-Ault and Megan Davies; Editing by Chris Reese)