While September carries a longstanding reputation as the “worst month of the year” for the S&P 500, Carson Group Chief Market Strategist Ryan Detrick argued that the market’s strong year-to-date trajectory suggests 2026 could defy those historical odds.
Historical Odds Favor the Bulls
Seasonal anxiety often peaks as September begins, but Detrick highlights that historical trends tell a far more optimistic story when equities enter the month on solid footing. Taking to X, Detrick acknowledged the seasonal reputation of September while pointing out key historical exceptions during strong market years.
“Yes, September is historically the worst month of the year. Get ready to hear that a lot next week,” Detrick posted. “But things do pretty well when August is green and the year is off to a solid start (up between 10% and 17.5%).”
Historical data stretching back to World War II reveals that when the S&P 500 achieves a positive August alongside year-to-date gains between 10% and 17.5%, a scenario matching 2026’s 3% August gain so far and 12.8% YTD return, September itself averages a 1.0% gain.
