Everyone is on edge these days, wondering when - it is only a question of when, based on history - the 10-year bull market will exhale and turn to a bear market.
Barron's recently signalled dark skies with headlines that read: "Stocks Threatened by Looming End of Low Rates" and "Four Questions About an Unloved Bull Market".
CNBC asks the question every day.
So does a buddy of mine at work.
"When is the end coming, Tommy?"
If I knew, by now I would be rich and parked in L'Hotel in Paris, washing down veal sweetbreads with a Manhattan of Bulleit Rye, a healthy shot of Rouge Dolin and spiced with a splash of orange bitters.
But I don't tell him that.
I simply throw up my arms with a clipped, "Who knows?"
And what would you do if it did tank? Say, overnight Facebook shares dropped from $160 to $50. Would you cut your losses and run? Selling all the stock?
Or would you seize the opportunity and buy all the stock you could?
"Suppose you were thinking of buying a new car. You went and you priced it and let's say the price was $28,000," said Terrance Odean, professor of finance at the Haas School of Business, at Berkeley. "If you went back a week later and the dealer said we have marked it down to $26,000, you would say, 'This is a deal. I'm glad I didn't buy it earlier.'"
Billionaire investor Warren Buffett famously put it this way: "When hamburgers go down in price, we sing the 'Hallelujah Chorus' in the Buffett household. When hamburgers go up in price, we weep. For most people, it's the same with everything in life they will be buying - except stocks. When stocks go down and you can get more for your money, people don't like them anymore."
I always like them - even when they dropped 38 per cent during the Great Recession.
I surprised myself.
For someone who bites his nails, I remained inordinately calm when my stocks tank and my net worth plunged. I tried not to look at the mutual fund tables. (I had a brief love affair buying individual stocks two decades ago. I was a naif. I bought a handful of blue-chip stocks, and I still have most of them. Boy, did I ever screw up on some of the others. But that's for another column.)
Anyway, my attitude on a stock market correction is that if the market never comes back, it means something worse is at work and I will have more serious problems to worry about such as war, famine, disease.
I am an optimist. I believe the market will endure.
But how long can it just go up and up and up?
"A well-deserved 5 percent correction could take place at any time, if for no other reason than it has been a year since the last 5 per cent correction," said Ryan Detrick, senior market strategist for LPL Financial. "This is only the sixth time since 1950 that the S&P 500 has made it at least a year without so much as a 5 per cent correction, and marks the longest streak since 1995."
There is human nature at work here. Minus a panic, investors tend to sell stocks high and grab the chips off the table. They are reluctant to sell below the purchase price because that means losing.
The anomaly is known as the "disposition effect."
The reluctance tends to disappear when a panic takes over and investors worry they may lose it all. That was one of the triggers of the Great Depression and the ensuing 25-year stock market hangover it ushered in.
"Investors often want to dump shares during a stock market crash because they want to cut their losses and because they fear even greater declines," said Kelly Shue, a professor of finance at the Yale School of Management.
If you are willing and able to tolerate low stock prices for 25 years, or even five years, you can buy and wait for the comeback.
"It's very difficult to predict when the market has bottomed out and when it will recover," Shue said. "It may be wiser to hold on and to avoid panic. Historically, stocks recover."
I am not smart enough to be a market timer. But I have a pulse. When the world was collapsing around the 2008 trough, I scooped up as much S&P 500-stock index mutual fund shares as I could afford.
Vanguard 500 Index Fund Admiral shares that sold for $63 in March 2009 are worth about $224 a share now.
I shoveled as much as I could of my paycheck into a Vanguard Index fund for at least two years - a savings strategy known as dollar-cost averaging.
Odean likes dollar-cost averaging. I don't mind it myself.
Thomas Heath is a business reporter and columnist, writing about entrepreneurs and various companies big and small in the US Washington Metropolitan area.