The Nasdaq and S&P 500 dipped on Tuesday driven by tech stocks, as investors gear up for what Federal Reserve chair Jerome Powell will say about the path of interest rates at a key conference later in the week.

Investors are tracking talks aimed at ending the Russia-Ukraine war and awaiting Federal Reserve Chair Jerome Powell's speech at Jackson Hole at the end of the week.

By Howard Schneider WASHINGTON (Reuters) -Fed Chair Jerome Powell used the central bank's annual Wyoming research conference to promise inflation-fighting rigor when it was needed in 2022, then last year he came to the defense of the job market with promises of lower interest rates when the unemployment rate seemed on a steady rise.