The U.S. stock market faces a Big Tech test this week, as the S&P 500 failed Monday to build on its sharp rally sparked by Federal Reserve Chair Jerome Powell’s Jackson Hole speech on Friday

Today, the blue-chip Dow Jones Industrial Average closed down 0.8% at 45,282, the broad-based S&P 500 was off 0.4% to 6,439, and the tech-heavy Nasdaq Composite lost 0.2% at 21,445.

AI bellwether Nvidia is slated to report quarterly results after markets close on Wednesday, and traders are prepared for the stock's biggest post-earnings move in more than a year.