Investors tired of the "sell in May" market cliché might want to consider replacing it with "buy at Lent," with stocks typically posting gains over the around 40-day period.
"Over the last 70 years or so, since World War II, we've seen about an average 2 percent gain and markets up 70 percent of the time between Ash Wednesday and Easter," said George Pearkes, an analyst at Bespoke Investment Group.
(Read more: 'Sell in May,' History Says: Pro)
"It's been especially true in the last 25 years. In the last five years, it's happened five times in a row. We see this as a pretty strong trend in seasonality," he told CNBC, although he added he didn't have an explanation.
The gains were particularly striking in 2009, when the S&P 500 ran up around 10.8 percent over the period, and in 2010, there was a 7.6 percent gain.