I’ve recently been seeing a certain defense of equities that I think is interesting. It runs something like this:

The recent rise in interest rates, which helped cause the stock market swoon, is actually a good thing because interest rates are rising due to a strong economy and increasing demand for capital, which pushes up interest rates. Therefore, stocks should actually not mind the increase in interest rates because it’s an indication of a strong economy.

This is a seductive argument. It’s wrong, but it’s seductive. Not only wrong, in fact, but wrong in ways that really shouldn’t confuse any economist or strategist writing in the last twenty years.

Up until the late 1990s, we couldn’t really tell the main reason that nominal interest rates were rising or falling. For an increase in market rates there are two main potential causes: an increase in real interest rates, which can be good if that increase is being caused by an increasing demand for credit rather than by a decreasing supply, and an increase in inflation expectations, which is an unalloyed negative. But in 1995, we would have had to just guess which was causing the increase in interest rates.

But since 1997, we’ve had inflation-linked bonds, which trade on the basis of real yield. So we no longer have to guess why nominal rates are rising. We can simply look.

The chart below shows the decomposition of 10-year nominal yields since early December. The red line, which corresponds to the left scale, shows “breakevens,” or the simple difference between real yields and nominal yields; the blue line, on the right-hand scale, shows real yields. So if you combine the two lines at any point, you get nominal yields.

Real yields represent the actual supply and demand for the use of capital. That is, if I lend the government money for ten years, then in order to entice me to forego current consumption the government must promise that every year I will accumulate about 0.68% more ‘stuff.’ I can consume more in the future by not consuming as much now. To turn that into a nominal yield, I then have to add some premium to represent how much the dollars I will get back in the future, and which I will use to buy that ‘stuff’, will have declined in value. That of course is inflation expectations, and right now investors who lend to the government are using about 2.1% as their measure of the rate of deterioration of the value of the dollar.[1]