Biden announced on Sunday he would drop out of the election race and endorsed Vice President Kamala Harris for the Democratic ticket.
Online betting site PredictIT showed pricing for a victory by Donald Trump had fallen 4 cents to 60 cents, while Harris climbed 12 cents to 39 cents.
Markets took the news in their stride, with S&P 500 stock futures nudging up 0.1%, while Nasdaq futures added 0.2%.
The MSCI All-World index, which fell 2.1% last week in its worst weekly performance since April, was narrowly in positive territory. The JSE's All Share Index gained 0.7%, with Sasol (+6%) and Amplats (3%) gaining ground after announcing a trading update and results, respectively..
The dollar held steady against a basket of currencies , while crypto - which has tended to be a beneficiary of the growing chances of a return of Trump to the White House - steadied after having fallen on Sunday following Biden's announcement.