If the election were held today, prediction site fivethirtyeight.com forecasts Democrat Clinton's chance of winning to be 52.1 percent, compared with Trump's 47.9 percent. On Monday, ahead of the debate, the site's forecast pegged Republican Trump's chance of winning at 51.9 percent to Clinton's 48.1 percent.
Their parties' respective presidential nominees clashed on Monday night on a wide range of topics, including the economy, crime, foreign policy and America's direction.
The debate was the first of three ahead of the Nov. 8 election, which has proved to be one of the most contentious and widely watched in modern history.
Markets also indicated Clinton won as the Mexican peso strengthened and U.S. stock index futures swung to positive territory after earlier losses.
Before the uptick, the peso had been steadily declining since Sept. 6, as Trump picked up steam in the polls ahead of the debate. Trump has focused much of his rhetoric on advocating for a tougher stance on immigration and building a wall between the U.S. and Mexico, a boundary he has insisted Mexico will pay for.
Clinton also pulled ahead in Google searches. During the debate, she urged viewers to visit her website, where staff would be fact-checking Trump's comments. Clinton dominated traffic in all 50 states afterward, reversing the pre-debate trend that favored Trump.
On October 17, Americans will get another read on the election after the WSJ/NBC News election poll publishes.