NEW YORK — Wall Street and financial industry executives urged caution overnight as no clear winner emerged in the hours after polls closed in the 2020 US presidential election, threatening a drawn-out count that keeps markets and businesses hanging.

While Republican President Donald Trump has handed the financial industry huge tax breaks and deregulatory wins, his first term has also been marked by volatility and unpredictability, particularly in international trade.

This year, the administration’s uneven response to the coronavirus pandemic also came under fierce criticism. The US economy slumped, with markets gyrating wildly and unemployment skyrocketing, as cities and states took different approaches to lockdowns to stop the spread of the virus.

Wall Street has been leaning left this election, with Democratic challenger Joe Biden outstripping Mr. Trump in financial industry fundraising. While many executives said they did not support all of Mr. Biden’s policies, they believed he would be more predictable and better for the country.

“This is a vote for the soul of our nation. Who we really are. Who we aspire to be,” Mike Novogratz, chief executive of New York-based Galaxy Digital and a major Democratic donor and fundraiser, tweeted early on Tuesday.

“Have to admit a feeling of Deja vu. Don’t like it. Still early though,” the former macro hedge fund manager tweeted later as results started to roll in showing the race still too close to call.

Global investors late on Tuesday began reversing some Biden trades that had prompted a jump in Wall Street’s main indexes earlier in the day.

Analysts expected record voter turnout, especially through mail-in ballots, which means it could take days to get certainty about a final tally. Both Mr. Trump’s and Mr. Biden’s teams said they were prepared to litigate the outcome.

Investors and fund managers said they were expecting a long night monitoring the results from home. For many, it was a far cry from Nov. 9, 2016 when, with no pandemic raging, New York city and other financial centers played host to countless informal watch parties in bars, and Trump’s victory was called at around 2.30 a.m.

This year, Mr. Novogratz tweeted about being at home with a bottle of wine, watching the results on television with his family. Max Gokhman, head of asset allocation for Pacific Life Fund Advisors, said he was working from his home in California, nursing a glass of bourbon and a cold brew coffee and not expecting to get any sleep.

Anthony Scaramucci, a hedge fund executive who spent 11 days as Mr. Trump’s communication director in 2017, said after many polls closed on the East Coast that the race would be closer than he initially thought but that he still expected Mr. Biden to win. Mr. Scaramucci, who became strongly anti-Trump following his brief White House stint, said he voted for the Democratic nominee.

“Yes, he can win and it will be very good for stocks.”

In anticipation of possible protests, some buildings and stores were boarded up in cities including Washington and New York. While there were few signs of disruptions or violence at polling sites on Tuesday, some finance executives said it was too soon to rule out civil unrest.

“There are no problems right now, but that’s only because there’s no answer right now,” said Billy Weber, CEO of Checkpoint Capital, a fixed-income platform.

The S&P 500 Index has risen 48.8% during Mr. Trump’s tenure, which he has frequently cited as a measure of success.

Policy-wise, the Trump administration has focused on lower taxes, deregulation and rethinking the US position on global trade agreements in order to boost domestic manufacturing.

Mr. Trump has not been uniformly loved, however, by the financial industry. He has attacked corporate leaders, including JPMorgan Chase & Co CEO Jamie Dimon, and close Wall Street associates have distanced themselves from Mr. Trump as he came under fire over his handling of the pandemic and racial justice protests.

Mr. Biden has called for higher corporate taxes, tougher regulation and a less combative stance with trade partners. The financial industry is also worried about an enforcement crackdown and an emboldened consumer watchdog, which Mr. Trump had diminished.

The former vice president has cast himself as someone who will unify the country and has aligned himself with progressives fiercely critical of Wall Street. But many financial executives said they were more worried about a second dose of Trump chaos.

Regardless of the winner, a decisive outcome was the key to giving Wall Street the certainty it craves, said David Boies, who represented Vice President Al Gore in the US Supreme Court case that put George W. Bush in the White House.

Still, some young Republican finance executives said they were anticipating gathering to celebrate Mr. Trump’s quick victory.

Charles Kolean, a 25-year-old investment industry worker who spent months raising cash to re-elect Mr. Trump, said he had reserved a chunk of a Dallas bar where he and some 100 friends planned to toast another four years for the president, albeit wearing masks.

“The perfect storm is coming together to make Donald Trump a two-term president.” — Reuters