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.
The Dow Jones industrial average held about 30 points lower, with UnitedHealth Group contributing the most losses. The S&P 500 fell about 0.2 percent, with health care lagging. Health care a day after posting 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 held about 0.25 percent lower.
"There is definitely a lack of volatility and a lack of volume in the market," said Fort Pitt Capital's Forrest.
Quincy Krosby, market strategist at Prudential Financial, said "I think [Yellen's] going to stick to her script that the Fed is data dependent," adding that Yellen may not want to tip her hand before the release of the August jobs report.
"It's difficult to believe she's going to be specific about a rate hike," she said.
Yellen is scheduled to speak Friday morning in Jackson Hole, Wyoming.