“The biggest down days tend to be followed by the biggest up days and this pattern once again is playing out,” Keith Lerner, co-chief investment officer at Truist Wealth, wrote in a note earlier this month.

Lerner looked at historically notable two-day slides in the market — 1987, a series of days in 2008, March 2020, April 3-4 — and found that each was followed by two-day bounces in excess of 9%. The 9.5% rally seen in the S&P 500 on April 9 fits the bill.

And should the US economy tip into recession, the one- and two-year returns from the market’s bottom tend to be memorable, with the S&P 500 averaging 40% and 54% over those periods, respectively. The S&P 500 averages an annual gain closer to 10%.

Noting that volatility spikes come in clusters has become de rigueur in discussing the stock market. And this new axiom also offers two distinct lessons for two different classes of investor.

For savers using the stock market’s long and growing history of usually going up over time, this volatility is the price of admission for realizing those gains.

A high-yield savings account, for instance, might offer someone 4% or so on their cash. The S&P 500 has offered investors closer to 10% a year the last 70 years. One return is, literally, money in the bank. The other is how you grow $10,000 into a million dollars in under 50 years.

For professional investors, these volatility clusters are reminders that the market falling off a cliff in a few short days is the time to lock in.

As Lerner highlighted in the same investor note, portfolios that miss the S&P 500’s best day since 1990 would lag those invested over the whole period by about 10%. Those missing the five best days would trail by over 35%. Miss the best 10 days, and your gains over the period are more than cut in half.

In other words, the data shows that out of the market’s biggest spasms come the market’s best opportunities. And that getting emotional around these big spasms can leave your portfolio trailing woefully behind your goals.