US Stock Market Outlook for September 2026: Three S&P 500 Scenarios

The S&P 500 entered September near 7,686 after closing August at 7,686.14. The index gained approximately 2.6% during August, recording its strongest August performance since 2021, but rising oil prices, elevated Treasury yields, and uncertainty surrounding Federal Reserve policy could produce larger market swings in September.
August began with the S&P 500 near 7,490 and was generally positive. Strong second-quarter earnings and continued investment in artificial intelligence helped the index reach record highs. S&P 500 companies were on pace to report adjusted earnings growth of 33.5%, the strongest increase since 2021.
However, the market lost some momentum late in August. On August 31, the S&P 500 declined 0.3% as Brent crude rose above $90 per barrel and the 10-year Treasury yield reached 4.75%. These developments increased concerns about inflation, borrowing costs, and geopolitical risks.
Positive scenario
If employment and inflation data show that price pressures are easing without a sharp…




