U.S. stock indexes declined modestly on Thursday as investors prepared for a highly anticipated speech by Federal Reserve Chair Jerome Powell at the Jackson Hole symposium on Friday. The S&P 500 fell 0.4%, the Nasdaq 100 dropped 0.5%, and Treasury yields rose amid reduced expectations for Federal Reserve rate cuts, driven by stronger economic data. Market participants are pricing in roughly an 80% chance of a September rate cut, but any indication from Powell that such easing is off the table could trigger increased volatility. Additionally, disappointing quarterly results from Walmart contributed to dampened market sentiment. Asian markets opened quietly in response to the cautious tone from Fed officials signaling potential restraint on monetary easing.