S&P 500 Historical Average September Decline Reaches 1.1%

The S&P 500 index has averaged a 1.1% monthly decline in September since 1928. This statistic places September among the weakest months for the benchmark. The Nasdaq Composite has shown a similar pattern with a 0.9% average drop since 1971.

The Dow Jones Industrial Average has averaged a 1.1% decline in September since 1897. It has posted negative returns in 57.8% of September months. The S&P 500 has finished in the positive in 44.9% of September months since 1928.

Market timing strategies underperform

Selling stocks to avoid September losses often results in missing strong recovery days. A 2025 Vanguard report states that bull market surges have been longer and stronger than preceding bear markets. The best and worst trading days often occur close together.

BlackRock CEO Larry Fink notes that staying invested matters more than timing. Every dollar invested in the S&P 500 over the past two decades grew more than eightfold. Missing just the ten best days would have earned less than half of that return.

Tax implications of selling

Selling positions in September can trigger taxable capital gains. Investors who sell and repurchase the same security face wash sale rules. They must wait more than 30 days to avoid tax penalties.

Long-term holding yields better results

Volatility is an inherent part of the stock market. Markets correct or crash occasionally, and recessions happen. Holding quality stocks for years or decades yields the best results. This strategy covers September and all other months.

A September market drop can create buying opportunities. Investors can purchase discounted shares of strong companies. GN auto markets/indices data supports the view that long-term holding outperforms short-term avoidance.