investors fretted over Britain's exit from the European Union.

The Dow Jones Industrial Average lost nearly half-a-percent,... the S&P 500 roughly the

same,... while the tech heavy Nasdaq edged down zero-point-two percent.

The dollar index,... which measures the greenback's performance against six major currencies,...

hit its highest level in almost two months.

The greenback has been on a strong footing from the start of the week,... and got a boost

following comments from Richmond Fed president Jeffrey Lacker who said there was a strong

case for raising rates.

Another focus of investors is Brexit -- after British Prime Minister Theresa May said the

UK would begin negotiations to leave the EU by March.

On that, the pound slumped to a 31-year-low.