Stocks ended Monday's session sharply lower as Wall Street grew restless ahead of the first presidential debate.
The S&P 500 was down 0.86%, the Dow Jones Industrial Average fell 0.91%, and the Nasdaq slid 0.91%.
Uncertainty over what economic policies Democratic presidential candidate Hillary Clinton and Republican candidate Donald Trump will push at Monday's debate caused market tremors throughout the session. Clinton and Trump will join ABC's Lester Holt for the first of three scheduled before voters head to the polls on Nov. 8.
"There are two political footballs to keep your eyes on: health care and energy," Stephen Guilfoyle, chief market economist at Stuart Frankel & Co., wrote in a note. "Depending on who appears to come out on top tonight could provide direction to these two sectors. Energy is a regulation play, while health care becomes about the perceived success or failure of Obamacare. These two candidates have very different ideas on these two areas, and an upper hand on Tuesday morning for either candidate could provide movement."
The health care sector was the worst performer on markets Monday. The industry's largest players including Johnson & Johnson (JNJ) , Merck (MRK) , Amgen (AMGN) , Gilead Sciences (GILD) and AbbVie (ABBV) were all lower, while the Health Care SPDR ETF (XLV) slid 1.2%.
Pfizer (PFE) fell nearly 2% after opting against splitting into two publicly traded companies. The drugmaker said its best action was to manage its two units, Pfizer Innovative Health and Pfizer Essential Health, under the one Pfizer umbrella. The company said that splitting up "would not enhance the cashflow generation and competitive positioning of the businesses" and that the cost of separating would be "value destructive."