First, this fall’s pullback is nowhere near as severe — at least not yet — as some of the major busts of the last two decades. The benchmark S&P 500 plunged nearly 57% during the 2008-09 financial crisis and nearly 49% in the dot-com crash of 2000-02. Those were bear markets, or drops of 20% or more from their previous highs.

Second, the triple-digit swings in the Dow industrials that garner big headlines — while truly unnerving a decade ago — are now more common because the market has climbed so high since then, and the declines are less severe on a percentage basis. By contrast, when the Dow plummeted 508 points on Oct. 19, 1987, for instance, it was a 22.6% loss — the largest single-day percentage drop on record.

In addition, the stock market reached its highest levels in history only a few months ago, and that was after the market soared in 2017, when the S&P 500 gained nearly 20% and the Nasdaq composite shot up 28%. As a result, it’s not surprising that investors would be willing to sell and capture those profits when signs of trouble surface.

Last year also was unusual for the dearth of volatility that is now again commonplace.