Feb
17John Rogers of Chicago-based Ariel Investments offers a useful illustration of the challenge in distinguishing skillful money managers from lucky stock pickers. Citing work by author and money manager Michael Mauboussin, Rogers suggests that the appropriate test of an activity where skill is rewarded is the extent to which a participant can lose on purpose. A chess grandmaster, for example, will beat a novice almost every time, but could choose to play badly enough to lose to anyone. In contrast, it would be impossible to lose consistently to a slot machine on purpose since the outcome is determined by chance alone.
Rogers decided to have some fun with this insight and asked 71 staff members of his investment firm to pick ten stocks that would underperform the market for the second quarter of 2009. Only 19 succeeded, meaning that 73% tried to lose on purpose but failed. The average return of the “loser” picks was 30%, compared to a total return of 15.93% for the S&P 500® index.
Like most professional stock pickers, Rogers is confident of his abilities and concludes from this experiment that “in companies and in portfolios, luck matters in the short term, but skill matters in the long term.” He cites no evidence to support the latter claim, and an alternative interpretation strikes us as more compelling: the difficulty experienced by Ariel employees in picking losers is just what we would expect to see if security prices, on average, are fair. And over any time period, it’s much easier to identify a grandmaster at chess than a skillful money manager.
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