Why Wednesdays and Fridays Outperform Other Trading Days in the S&P 500
The stock market has long been the most powerful tool for building wealth over time. Data stretching back more than a century confirms its dominance over other asset classes. Yet not all trading days perform equally—some have consistently favoured investors more than others.
Since 1900, every rolling 20-year period in the S&P 500 has delivered a positive annualised return. This track record reinforces the idea that patience and persistence pay off. Missing even a handful of the market's best days, however, can severely cut into long-term gains.
Certain days of the week have shown clear patterns. Wednesdays have historically been the strongest, with an average S&P 500 return of 0.06% since 1928. Fridays come close behind, finishing positive 54.6% of the time—the highest probability of any weekday. Mondays, on the other hand, have averaged a slight loss of -0.07%, with over half of all trading Mondays closing lower. Even superstitions don't hold up under scrutiny. Friday the 13th, often feared as unlucky, has actually seen an average S&P 500 return of 0.09% since 1928. If annualised, that figure would translate to a 22.4% return. Records also suggest fewer than half of these supposedly cursed days ended in the red.
The numbers leave little doubt: the stock market remains the top wealth generator over the long run. While some days—like Fridays and Wednesdays—have historically offered better returns, the real key to success lies in staying invested. Time, not timing, has proven the most reliable path to growth.
