You’ve heard of “irrational exuberance,” right That’s the expression Alan Greenspan coined more than a decade ago when he warned that investors could be bidding stock prices too high. His worry was that escalating asset values were trumping reality.

These days, the opposite seems to be the case. Call it “irrational pessimism,” a fear that stock prices are headed in only one direction-lower and lower-because asset values and profits seem certain to fall.