Something else that isn't a stock-market indicator.                                          Photo by Popperfoto/Getty Images
Something else that isn't a stock-market indicator.                                          Photo by Popperfoto/Getty Images

Last month, we discussed how we might be on the verge of a correction. We also noted the futility of trying to time the start and finish of such events. What actually matters is how you react -- or overreact.

As my colleague Josh Brown has observed, “since the end of World War II (1945), there have been 27 corrections of 10 percent or more, versus only 12 full-blown bear markets (20 percent or worse).”

However, the data show that the distribution of corrections isn't smooth. Indeed, almost half (45 percent) of the corrections occurred either in the 1970s or the 2000s. Both eras were part of longer-term secular bear markets, characterized by strong rallies, vicious sell-offs and earnings contractions.

It is noteworthy that almost half of the corrections occurred in two out of seven decades. I suspect this fact isn't a coincidence. From a 30,000 foot view, it may be a key to understanding how likely a more severe correction might be.

Consider the various narratives that have been used as an excuse for a correction. The downgrade of U.S. debt by Standard & Poor's was going to be a deathblow; it wasn’t. Treasuries rallied on the downgrade, just to prove that no one knows nuthin’. The sequestration of government spending was sure to cause a slow down in markets; it didn’t. Rising interest rates, the Federal Reserve's taper, earnings misses, and of course, our winter of discontent, were all cited as triggers for corrections. And did I mention the Hindenburg Omen?

The punditry then shifted to valuations: We have heard repeatedly that markets are wildly overpriced, that we are in a bubble. Or if not a broad market bubble, then a tech bubble or an initial-public-offering bubble or a merger bubble. Some advanced the theory that Twenty-First Century Fox’s bid for Time Warner was itself proof of a top.

None of those claims gained much traction. The next set of catalysts for disaster was geopolitical. Russia's annexation of Crimea was going to cause a spike in oil prices and a crash -- only it didn’t. Then came the imminent invasion of Ukraine. UBS’s Art Cashin buried that trope yesterday. The Israel-Gaza war is another source of potential oil spikes and market crashes, which have yet to come to pass.

Now, today’s weak futures are blamed on the threatened U.S. airstrikes on ISIS, dragging America into another Middle East war. Each time I think I have finally put George W. Bush’s misadventures out of my mind, something comes about to remind us how utterly bereft of reason or intelligence the decision to invade Iraq was. It is likely to haunt the U.S. even longer than the disastrous Vietnam War.

But is that what is driving the markets? Probably not.

The simple reality is that corrections come along on a regular basis, and for reasons that are undecipherable or indeterminate. This is the way it is and always has been. Anyone who tells you he can predict when a 5 percent or even 10 percent correction is going to start and end, and do so with any degree of consistency, has something very expensive and mostly worthless to sell you.

Almost 500 trading days have passed without a 10 percent retreat. If you have grown so complacent as to have forgotten this, then you might very well be in the wrong line of work.

Corrections happen. Get used to it.

To contact the author of this article: Barry Ritholtz at britholtz3@bloomberg.net.

To contact the editor responsible for this article: James Greiff at jgreiff@bloomberg.net.