What Price Risk? Unpacking the Equity Risk Premium
Editor’s Note: This is the second in a series of articles that challenge the conventional wisdom that stocks always outperform bonds over the long term and that a negative correlation between bonds and stocks leads to effective diversification. In it, Edward McQuarrie draws from his research analyzing US stock and bond records dating back to 1792. CFA Institute Research and Policy Center recently hosted a panel discussion comprising McQuarrie, Rob Arnott, Elroy Dimson, Roger Ibbotson, and Jeremy Siegel. Laurence B. Siegel moderated. The webinar elicits divergent views on the equity risk premium and McQuarrie’s thesis. Subscribe to Research and Policy Center, and you will be notified when the video airs. Edward McQuarrie: My inaugural post on the equity risk premium presented a new historical account of US stock and bond returns that tells a different, more nuanced story than the account offered by Siegel in his seminal book, Stocks for the Long Run, now in its 6th edition. This blog series stems from my Financial Analysts Journal article, “Stocks for the Long Run? Sometimes Yes, Sometimes No,” which is open for all to read on Taylor & Francis. A reader of my first post objected to my conclusions, arguing that the 19th century US data presented was just too far in the past to be meaningful to investors today. I anticipated that objection at the end of my last post. Here, I refute that notion with the help of recent international data. New International Data is Available When Siegel began his work in the early 1990s, international market history was more terra incognita than 19th century US market history. In recent years, Elroy Dimson and his colleagues have shed light on historical returns. In 2002, they published Triumph of the Optimists, an account of 15 markets outside the United States, replete with historical returns on stocks and bonds dating back to 1900. The Dimson-led effort was not the only expansion of the international record. Bryan Taylor at Global Financial Data, and Oscar Jorda and colleagues at macrohistory.net, have also developed historical databases of international returns, stretching back in some cases to the 1700s. Indeed, many financial historians, including William Goetzmann, Editor of the Financial Analysts Journal, have spent entire careers digging into historical data to extract insights that shape our evolving understanding of markets and their role in shaping society. A few years after Triumph‘s publication, the Dimson team began to update and expand their database on an annual basis, producing a series of yearbooks, most recently the 2024 edition. Along the way, they’ve expanded the markets covered. Triumph had been criticized for survivorship bias, i.e., including only the markets that fared reasonably well and excluding markets that went bust, such as Russia in 2017 and those that fizzled, such as Austria after the war. Most important, the Dimson team began to calculate a world ex-US index of stock and bond performance, allowing a better assessment of the differences between US stock returns and returns elsewhere. None of this data had been compiled when Jeremy Siegel started out. I presented portions of it in my paper as an out-of-sample test of the Stocks for the Long Run thesis. The United States in Context The 120-year annualized real return on world stocks ex-US is now estimated by the Dimson team to be approximately 4.3%. Siegel estimated real long-term returns of 6% to 7%. That difference does not sound like much, but Dimson and colleagues note: “A dollar invested in US equities in 1900 resulted in a terminal value of USD 1937 … An equivalent investment in stocks from the rest of the world gave a terminal value of USD 179…less than a tenth of the US value.” We might say that international investors suffered a 90% shortfall in wealth creation. Regime Switching A key concept in my paper is the idea of regime switching, when asset returns fluctuate through phases that can last for decades. In one phase, bonds may perform terribly, as seen in the United States after World War II. In another phase, stocks may languish, as seen in the United States before the Civil War. Because returns are not stationary in character, it may not be useful to calculate asset returns over centuries and sum these up by offering one single number. In my view, there’s too much variance for one number to offer investors meaningful guidance, or to set expectations for what might happen over their unique horizons. The Range of Returns: the Good, the Bad, and the Ugly Here is an analogy to highlight the problem. Let’s say that the 100 students who attended my lecture this morning had their shoes ruined. The carpet cleaner last night used a solvent rather than the intended cleaning solution. This caused the carpet to lift in patches, which bonded to the students’ shoe soles. The University wishes to make amends by purchasing a new pair of shoes for each student. As an academic educated in statistics, I suggest to administrators that they simplify their task by buying 100 pairs of shoes all in the average shoe size, because the mean gives the best linear unbiased estimate. How many students will be happy with their new shoes? Returning to market history, what investors need to understand is the range of returns, not the all-sample average. Investors need to grasp how much returns can vary over long time horizons that correspond to the periods over which they might seek to accumulate wealth, such as 10-, 20-, 30-, or 50-year spans. The accepted approach for doing so is to calculate rolling returns. Thus, we can look at the set of 20-year returns: 1900 to 1919 inclusive, 1901 to 1920, 1902 to 1921, etc. Rolls allow us to examine how investors fared across all available starting points: the good, the bad, and the ugly. In my paper I looked at 20-, 30-, and 50-year returns for 19 markets outside the US, using data as far back as were available. First, however, we need to deal with an objection that quickly
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