Polls this spring have consistently shown Joe Biden with a lead over President Trump but betting markets have had Trump ahead almost the entire time. This RealClearPolitics chart shows Biden had a very slight and momentary lead right after he effectively wrapped up the Democratic nomination in mid-March, but otherwise Trump has had a clear lead throughout. As recently as May 24 (the day before George Floyd was killed in Minneapolis), Trump enjoyed an eight-point lead over Biden in betting markets.
That changed this week; with the latest polls showing Biden up anywhere from six to eleven points, bookmakers are now agreeing with the pollsters and giving Biden a slight edge. The RealClearPolitics survey of oddsmakers gives Biden a 3.8 percent lead over Trump.