U.S. equities closed around breakeven on Monday, after gyrating between slight gains and losses as an investigation into new Hillary Clinton emails kept investors on edge.
The Dow Jones industrial average closed about 20 points lower, with Goldman Sachs contributing the most gains and Nike the most losses. The index also posted its narrowest single-day trading range since September 7 and the third-narrowest of 2016.
The S&P 500 fell less than a point, despite utilities rising about 2 percent. The Nasdaq composite closed just below breakeven.
Monday was also the last day of October, with the Dow and S&P extending their slide to three months, while the Nasdaq snapped a three-month winning streak.
"Punch drunk from the highly unanticipated Brexit outcome, institutional investors will take a wait and see approach until they have more clarity on how the balance of power in Washington will settle," said Jeremy Klein, chief market strategist at FBN Securities.
FBI Director James Comey said in a Friday letter to lawmakers that the agency is probing new emails related to the Democratic nominee. The emails were discovered during a separate investigation involving former Congressman Anthony Weiner.
"The market has been pricing in a Hillary Clinton victory and that got thrown into disarray," said Randy Frederick, vice president of trading and derivatives at Charles Schwab. "I think everybody is going to be glued to the news with this Hillary Clinton email scandal. The S&P fell 20 points in a second" on Friday.
"I think we're entering a period of uncertainty," said Peter Cardillo, chief market economist at First Standard Financial. "The prospects of a Clinton win leading to a Clinton resignation would be on the minds of people if she wins. A Trump win, on the other hand, can bring a whole new set of concerns. I think it's a no-win situation in the short term."