US stocks closed lower on Wednesday, with health care shedding more than 1.5%, while investors eagerly awaited a speech from Federal Reserve Chair Janet Yellen.

    The Dow Jones industrial average closed 65.82 points lower, or 0.35%, at 18,481.48, with UnitedHealth Group leading decliners and Nike the biggest riser.

    The S&P 500 fell 11.46 points, or 0.52%, to 2,175.44, with health care leading nine sectors lower and utilities closing flat. The Nasdaq dropped 42.38 points, or 0.81%, to 5,217.69