In my previous article on valuing the U.S. stock market, we looked at Warren Buffett’s favorite valuation measure, total market cap to GDP. We learned that, according to this ratio, stocks are indeed overvalued today. We also learned that stocks could continue to be overvalued for an extended period of time before a correction materializes. In short, there are a number of good methods to measure the market’s current valuation. However, because investors are not rational, a correction can occur at any point, even when valuation ratios are close to fair value.
In this article, we’ll look at two additional market valuation tools, Tobin’s Q Ratio and Robert Shiller’s C.A.P.E. Ratio. Like Buffett’s favorite, these paint a similar picture of the current stock market. Even so, when used in conjunction, they can provide great insight into an issue that is on the mind of many investors: where does the market go from here?
Valuation Measure: Tobin’s Q Ratio
Tobin’s Q Ratio was developed by James Tobin, recipient of the 1981 Nobel Prize in Economic Sciences. Tobin earned his first post-secondary degree in 1939, his M.A. in 1940, and his Ph.D. in 1947, all from Harvard University. His brilliance influenced many in the field of economics, and one of his most lauded contributions is his Q Ratio which compares an asset’s market value to its replacement value. The numerator contains the asset’s fair market value and the denominator is the asset’s replacement value. Here it is expressed as an equation:
Tobin’s Q Ratio = Fair Market Value / Replacement Value
Although it’s not an exact match, it has become common to calculate the ratio as follows:
(Equity Market Value + Liabilities Market Value) / (Equity Book Value + Liabilities Book Value)
To interpret the ratio, if a company’s market value is equal to its book value, it would be considered fairly valued. If a company’s market value is greater than its book value, it would be considered overvalued. The following chart contains the ratio from the fourth quarter 1949 through the third quarter 2014. The data is derived from the Federal Reserve report: Z.1 Flow of Funds Accounts of the United States. It is found in Table B.102, lines 35 and 32.
As you can see, the ratio was in extreme territory during the tech bubble, reaching a record high of 1.775. For a little perspective, its long-term average is 0.743. Leading up to the housing bubble, it was actually under 1.0, indicating stocks were slightly undervalued. Today, it’s in mildly over-valued territory, but nothing which would be considered alarming. Considering that it was low when the housing bubble burst and stocks plummeted, one must wonder about the efficacy of this particular ratio. Let’s move on to the next valuation measure.
Valuation Ratio: Shiller’s C.A.P.E. Ratio