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when Jeremy seagull published his stocks for the long run thesis little was known about 19th Century stock and bond returns digital archives have made it possible to compute real Total return on us stock and bond indexes from 1792 the new historical record shows that over multi- deade periods sometimes stocks outperformed bonds sometimes bonds outperformed stocks and sometimes they performed about the same new international data confirm this pattern asset returns in the United States in the 20th century do not generalize regimes of asset outperformance come and go sometimes there is an equity premium sometimes not the 120-year annualized real return on stocks X United States is now estimated by the Dimson team is 4.4% not the 6.6% estimated by seagull as the true long-term expected value that difference does not sound like much but is the 2020 credit swe yearbook notes a dollar invested in US equities in 1900 resulted in a terminal value of $1,937 an equivalent investment in stock from the rest of the world gave a terminal value of $179 less than a tenth of the United States value the favorable experience of United States stock investors in the 20th century does not generalize stock wealth accumulated by the long term International investor has fallen 90% short of expectation the new historical record addresses a can drum that gradually emerged as the work of Roger ibbertson and Jeremy seagull diffused to a broader public if stocks are risky investors will demand a premium to invest but if stocks cease to be risky once held for a long enough period if stocks are certain to have strong returns after 20 years and certain to outperform bonds then investors have no reason to expect a premium over these longer periods given that no shortfall risk had to be assumed the expanded historical record shows that stocks can perform poorly in absolute terms and underperform bonds whether the holding period is 20 30 50 or 100 years that documentation of risk resolves the conundrum there can be no equity premium unless stocks are risky but with that risk documented even if in frequent incurrence investors can based on the entirety of the historical record probabilistically expect stocks to outperform bonds over other intervals including the interval that corresponds to their own investment Horizon conversely if stocks had never done poorly outside of war and disaster there would be no reason to expect stocks to continue to do well in peace time because no shortfall risk would have been demonstrated the fact of a persistent Equity premium and not just its level would be the puzzle once investors accept that stocks can disappoint no matter the interval Diversified portfolios become more attractive in inhibiton seagull World any portfolio not 100% in stocks must underperform over the long term but if sometimes stocks do well and sometimes not investors can justify diversifying away from a 100% stock position
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