One answer is that last fall many investors were looking at a couple of quarters of high growth, and thinking that this might be the start of an extended boom. Serious economists warned that this growth was a temporary lift — a “sugar high” — driven by the shift from fiscal austerity to what-me-worry deficit finance. But at least some people bought into the Trumpist line that tax cuts were going to produce an enduring rise in the growth rate.

Since then, however, it has become clear that the tax-cut boost was indeed a one-time thing. In particular, there has been no sign of the promised surge in business investment.

At the same time, Trump’s trade war may be starting to take a toll. In particular, the uncertainty may be deterring business spending. Whether new tariffs would hurt or help your business, it now makes sense to hold off on plans to expand, until you see what he actually does.

Finally, economic troubles in the rest of the world — several major European economies are quite possibly in recession — are filtering back to the U.S.

Now, most economists aren’t predicting a recession here, for good reason. The truth is that nobody is very good at calling turning points in the economy, and calling a recession before it’s really obvious in the data is much more likely to get you declared a Chicken Little than hailed as a prophet. (Believe me, I know all about it.) But the bond market, which doesn’t worry about such things, is looking remarkably grim. I leave the possible political implications as an exercise for all of you.