The U.S. dollar was little changed on Wednesday as traders awaited a speech from Federal Reserve Chair Jerome Powell at the annual Jackson Hole central bankers' symposium later this week for clues on the path of monetary policy.

This week's set-piece event is the Jackson Hole central-bank gathering in Wyoming, slated for Thursday through Saturday. Investors will tune into Federal Reserve Chair Jerome Powell's speech for any hints on whether the central bank might kick off interest-rate cuts in September.

The Nasdaq fell as megacaps lost, after having rallied for much of the year. Nvidia fell 3.5%, the biggest drop in nearly four months.

The U.S. dollar hovered below a one-week high on Thursday and European stock markets opened flat as investors braced for three days of potentially market-moving news from the Federal Reserve's annual symposium in Jackson Hole.