Around $750 Billion Erased From U.S. Stock Market In About 60 Minutes Following Headlines On Iran–U.S. Nuclear Talks S&P 500 Down 1.13% Nasdaq Down 1.76% Dow Down 0.28% Russell 2000 Down 0.55% Markets Reacted Quickly To Renewed Geopolitical Uncertainty, With Broad Indexes Turning Lower As Investors Repriced Risk.