Can Individual Investors Beat the Market?
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What they found
Using the same discount-brokerage dataset as Barber and Odean (1991 to 1996), the authors asked not whether the average investor beats the market but whether any do persistently. They found that investors whose trades performed well in one period continued to outperform in the next: the top decile of traders by past performance earned abnormal returns of about 15 basis points per day on subsequent purchases, and the persistence was too strong to be explained by luck or by known return anomalies. A strategy of mimicking the trades of the most skilled individuals would have been profitable.
What you can use
- Skill among individual investors exists and is persistent; the average is poor, but the top group is genuinely good and stays good.
- The persistence shows up in the returns of the specific stocks skilled investors buy, so the edge is in selection, not just in restraint.
- The paper circulated for nearly twenty years before publication and is the best-known evidence that 'individuals cannot beat the market' is too strong a claim.
Caveats
1990s data from one broker; the skilled group is a small fraction of the sample. Persistence was measured on subsequent trades, not whole-portfolio returns. Open-access journal version.
Tags: professional, retail, skill, persistence
Summaries are our own reading of the paper, not the authors' words. Educational only, not advice. Discuss it in Book Club.