The S&P 500 reached a new record high in September 2025, bolstered by a Federal Reserve rate cut and a major tech investment. On September 17, the Fed lowered the primary interest rate by 0.25 percentage points, citing a weakening labor market. This decision boosted investor confidence and reduced borrowing costs, sparking a stock market rally. Additionally, Nvidia's $5 billion investment in Intel significantly impacted the tech sector, with Intel's stock price surging over 30% in premarket trading. The S&P 500 marked its 26th record close this year, setting the stage for a robust third-quarter performance in the U.S. stock market.