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Commentary by Kevin DiCiurcio, CFA, Vanguard senior investment strategist

Since the remarkable equity market reversal in developed countries in late March, many clients have asked whether markets have become irrational. Given the extreme uncertainty surrounding Covid-19, rising unemployment and eye-watering declines in second-quarter GDP, how can US equities have hit1 all-time highs?

Possible answers range from the idea that “there’s no alternative”, given low interest rates, to young investors’ driving the market through new digital investor platforms. Our Investment Strategy Group, however, thinks that the answer is fundamental. And we don’t believe that US equity markets are acting irrationally.

Mathematics and value judgments

At their core, financial markets reflect today’s assessments of asset values based on investors’ expectations for the cash those assets will generate in future. This concept of net present value is more concretely applied to fixed income, where the known values for bond yields and coupon payments produce the price. Knowing two of the three values allows investors to determine the third. 

The concept applies equally to equity markets. Price plays the same role as in fixed income; future cash flows equate to a bond coupon, and the required rate of return equates to the yield to maturity of a bond. The challenge for equities is the inherent uncertainty around future cash flows—the earnings that companies will reinvest in the business or distribute in dividends.

Much of the assessment of these future cash flows is related to current financial conditions. Because of the market’s forward-looking nature, prices react to changing corporate and economic conditions faster than traditional economic data can.

Three telling events

Though Covid-19 remains a real risk to the global economy, three important things happened in recent months to cause equity markets to reassess return prospects after the fall into bear-market territory. Long-term bond yields declined steeply, the Federal Reserve cut its policy rate to zero, and already-low inflation expectations fell even further. These factors caused the required rate of return to plummet. The present value of equities increases as the required rate of return decreases.

A fair value for US equities

A fair value for US equities

Notes: Vanguard’s US fair value CAPE framework is based on a statistical model that corrects measures of cyclically adjusted price-to-earnings ratios for the level of inflation expectations and for interest rates. The statistical model includes equity-earnings yields, ten-year trailing inflation and ten-year US Treasury yields. For details, see Vanguard’s Global Macro Matters paper As US Stock Prices Rise, the Risk-Return Trade-Off Gets Tricky (Joseph Davis, 2017). 

Sources: Vanguard calculations as of 31 July 2020, based on data from Robert Shiller’s website at, the US Bureau of Labor Statistics, the Federal Reserve Board, and Global Financial Data.

Vanguard has developed a proprietary framework to model the relationship among equity valuations, long-term bond yields and inflation – fair value CAPE (cyclically adjusted price-to-earnings ratio). The model shows a fair value range that has moved higher since the first quarter. Interestingly, the S&P 500 CAPE at the end of July falls right in the middle of this range, meaning that valuations as of that date are fair based on interest rates and inflation, which we view as a proxy for the required rate of return.

As for the future . . .

What does this mean for future equity prices? That depends. A higher fair value range now won’t necessarily remain elevated or continue to increase. Nor does it mean that market prices won’t deviate from fair value temporarily. A normalisation in interest rates and inflation expectations would cause fair value to fall (all else being equal), but prices may not immediately follow because of other short-term factors. Over longer periods, though, we’d expect these deviations to revert to fair value as they have over the past 70 years, as shown in the chart.

Vanguard’s global economics team doesn’t expect monetary policy to normalise anytime soon. On the contrary, we believe the federal funds rate will remain near zero at least until the end of 2021. We also believe that demand-supply imbalances will likely lead to lower (not higher) inflation in developed countries for the foreseeable future, despite unprecedented monetary and fiscal policy. This would suggest that fair value is unlikely to change significantly.

Better-than-expected news about the development of a vaccine or effective therapy could cause equity prices to deviate into overvalued territory. Conversely, if these developments take longer or containment measures prove unsuccessful, prices could move into undervalued territory as market sentiment suffers.

Accurately predicting such surprises and untangling them from market prices is difficult at best. We may not be able to predict the market’s next move with any degree of confidence, but we can say that a reasonable basis exists for recent levels.


The writer would like to acknowledge the contributions of Kelly Farley and Ian Kresnak, CFA, to this commentary.

1The S&P 500 set a closing record on 18 August 2020. The valuation measures discussed in this article are, however, as at 31 July 2020.

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