Wall Street's main indexes fell on Thursday as investors awaited monetary policy clues from the Federal Reserve's annual economic symposium, while big-box retailer Walmart's quarterly results dampened sentiment.

Households earning more than $100,000 made up 75% of the company’s market share gains in the fiscal third quarter, Walmart CEO Doug McMillon said on the company’s earnings call in November.

The investing world will turn its attention to northwestern Wyoming in the week ahead, with Federal Reserve Chair Jerome Powell set to give his most important policy speech of the year on Friday at the annual Jackson Hole Economic Symposium.