The Dow Jones industrial average closed more than 600 points lower Friday, only the ninth time in history that has happened.

The index posted a loss of nearly 666 points, its sixth-worst decline ever on a points basis.

The last time the index posted a drop of more than 600 points was June 24, 2016, the day after the Brexit vote.

The eight other times the Dow closed more than 600 points lower all took place in the last 18 years. Half occurred during the financial crisis in 2008.