Since the start of this decade, the S&P 500 is now down -2.9% (toss in dividends, it’s up +11.7%). However, investing in just the first day of the month has delivered a return of 35.4%.
I should add that the out-performance is not just due to the market’s implosion at the beginning of the decade. As the market turned around, the first day of the month held its own. From March 11, 2003 to October 9, 2007, the S&P 500 gained 95.5%. The first day of the month gained 25.2%.That’s a pretty heft contribution from just one day in the month. Consider that on the trading calendar, the first day of the month is less than 5% of the time.