The United States stock market is trading at a very high level today. The data show where the market stands, but don’t tell us how it got there. For an explanation of that, we need to take into account a factor that sound very unscientific: “animal spirits,” sometimes called “gut feelings.”
First, let’s look at some of the numbers. More than 30 years ago, the economist John Campbell and I developed what we have called the Cyclically Adjusted Price Earnings (C.A.P.E.) ratio, a measure that enables the comparison of stock market valuations from different eras by averaging the earnings over ten years, thus reducing some of the short-term fluctuations of each market cycle. C.A.P.E. reached 33 in January 2018 and is almost as high now, at 31. That number might seem meaningless in itself, but it is significant when you consider that it has been as high or higher on only two occasions: 1929, just before the 85 percent stock market crash ending in 1932, and in 1999, just before the 50 percent drop at the beginning of the new millennium.
People will point this year to low interest rates to justify the high C.A.P.E. ratio. But interest rate levels historically have not correlated well at all with the C.A.P.E. For example, low long-term rates did not explain the high C.A.P.E. ratios in 1929 and 1999, nor did rising long-term interest rates explain subsequent market crashes.
That brings us to another factor, which John Maynard Keynes called “animal spirits.” It is a sense of optimism and ready energy to be entrepreneurial and take risks, and it has been adjudged to contribute to high stock market levels. Animal spirits are not adequately measured by business consumer confidence indexes, because the surveyors do not probe for such deep feelings.
High animal spirits in the stock market are often associated with the disparagement of traditional authority and expert opinion. This popular narrative often advocates relying on your “gut feelings” to try what experts say is doomed to failure.
President Trump uses this kind of language. Recently, for example, he said “I have a gut, and my gut tells me more sometimes than anybody else’s brain can ever tell me.”