U.S. equities closed lower Thursday, with health care falling approximately 1 percent, a day ahead of a key speech from Federal Reserve Chair Janet Yellen.
"If all eyes are going to be on Janet Yellen tomorrow, everyone's going to be disappointed," said Art Hogan, chief market strategist at Wunderlich Securities. " She hasn't stumbled into tipping her hand yet, and she's been on the job for a few years."
The Dow Jones industrial average closed about 30 points lower, with UnitedHealth Group contributing the most losses. The S&P 500 fell about 0.1 percent, with health care lagging. The sector had posted its worst day since June 24 on Wednesday.
"If we look back to last year, it looks like history is repeating itself," said Mike Bailey, director of research at FBB Capital Partners. "I think investors need to be cautious on health care."
The sector fell Wednesday after presidential candidate Hillary Clinton tweeted about Mylan's price increases of the allergy drug EpiPen. Mylan shares were down more than 1 percent in afternoon trade.
But "until we see what kind of Congress we get, none of that is meaningful," said Kim Forrest, senior equity analyst at Fort Pitt Capital.
The Nasdaq composite closed about 0.1 percent lower, and posted its first two-day losing streak since late June.
"There is definitely a lack of volatility and a lack of volume in the market," said Fort Pitt Capital's Forrest.