I was reading an article on Yahoo Finance the other day that cited what it claimed was a Warren Buffett rule to gauge whether the US stock market is under- or overvalued. The idea is that if the total market cap of US stocks exceeds annual GDP (of the US) then stocks are overvalued. If market cap is less than GDP, stocks are undervalued.
On the surface, this sounds like it might make sense, since it is the US stock market, after all. And the health of the Treasury bond market is tied to the vigor of the US economy. Also, the idea was big in the 1980s, when market cap/GDP was used by Americans and Europeans as a rationale for not becoming involved in the Japanese stock market during a decade-long domestic economy boom there.
Two issues this idea ignores:
–multinational companies. In the case of the US, a good guess is that half the earnings of the S&P 500 come from outside the US. In fact, a very simple but effective way of approaching structuring a portfolio in the US market is to ask whether the US economy will likely do better than the rest of the world in the year ahead or worse. In the first case, the portfolio should overweight domestic-oriented stocks; in the second, internationally-oriented.
–how much of the domestic economy is publicly traded. In the case of the US, big sectors like real estate and housing have little representation. Germany, whose market cap has seldom, if ever, exceeded half of the country’s GDP, is the biggest counterexample for the cap/GDP idea. Two reasons: almost nothing is listed in Germany, and German citizens have historically had little interest in stocks.
For the record, I can’t imagine Buffett thinks this.
strong stock market = strong economy
Typically, this is the case, in my experience. But there are exceptions, like Mexico in the 1980s–and Germany almost always. In today’s US, it’s easy to see, by comparing the global NASDAQ with the US-centric Russell 2000, that stocks are strong in spite of weakness in domestically-oriented issues. In fact, somewhat like Mexico back then, the US market is underpinned by the near-zero interest rates made necessary by our extreme economic weakness.
A side note: over the past three months, the R2000 (+22.7%) has held its own with NASDAQ (+24.5%). Both have far outdistanced the S&P 500 (+17.5%). Why the R2000 strength? Three possible reasons (translation: I don’t know): counter-trend rally; the worst of the pandemic is already baked into R2000 prices; anticipation that Trump will not be reelected. My guess is some combination of the first two. I think it’s too early to be trying to figure out the election, although belief in four more years of Trump dysfunction should translate into shorting the dollar and the R2000.