# Overtrading Destroys Returns: Why the Most Active Individual Investors Earn the Least

Cite as: Gorak, R. (2026). Overtrading Destroys Returns: Why the Most Active Individual Investors Earn the Least. Tradicted. https://www.tradicted.com/research/barber-overtrading-2000/
Paper: Brad M. Barber and Terrance Odean — *Trading Is Hazardous to Your Wealth: The Common Stock Investment Performance of Individual Investors*
Published in: Journal of Finance (2000)
Original: https://faculty.haas.berkeley.edu/odean/papers%20current%20versions/Individual_Investor_Performance_Final.pdf

Key finding: Of 66,465 households at a large discount broker from 1991 to 1996, those in the highest turnover quintile (monthly turnover >8.8%) earned a net annualized geometric mean return of 11.4 percent, while the lowest turnover quintile earned 18.5 percent and the market returned 17.9 percent.

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Overtrading describes the pattern in which individual investors trade actively enough to reduce their net returns below passive market returns. A household turning over 75 percent of its portfolio per year incurs about 4 percent in round-trip transaction costs on every trade over $1,000. In *Trading Is Hazardous to Your Wealth*, Barber and Odean (2000) analyzed 66,465 households at a large U.S. discount broker, 1991–1996. The most active quintile earned 11.4 percent net annually; the market returned 17.9 percent and the least active quintile earned 18.5 percent.

## What the Study Found

The most active turnover quintile (avg monthly turnover 21.49%) earned a net annual return of 11.4 percent versus 17.9 percent for the market. The least active quintile (avg monthly turnover 0.19%) earned a net annual return of 18.5 percent. The average household earned 18.7 percent gross but only 16.4 percent net, turning over more than 75 percent of its portfolio annually. The Fama-French net return spread between the high and low turnover quintiles is 80 basis points per month (9.6 percent per year; t=−4.59). Only 43.4 percent of households outperform the value-weighted index after transaction costs, compared with 49.3 percent before.

## Methodology

The dataset is proprietary position statements and trade records for 78,000 households at a large discount brokerage firm; 66,465 held common stocks. The sample period is January 1991 through December 1996, with returns measured from February 1991 through January 1997. Households are sorted into quintiles by mean monthly turnover; performance is measured gross and net of commissions and bid-ask spread. Risk-adjusted returns are estimated using CAPM (Jensen's alpha), the Fama-French three-factor model, and own-benchmark abnormal returns.

## Key Statistics

| Metric | Finding | Context |
|---|---|---|
| Value-weighted market return | 17.9% annualized | NYSE/AMEX/Nasdaq; February 1991 through January 1997 |
| Most active quintile net return (Q5) | 11.4% annualized | Avg monthly turnover 21.49%; net geometric mean |
| Least active quintile net return (Q1) | 18.5% annualized | Avg monthly turnover 0.19%; net geometric mean |
| Average household net return | 16.4% annualized | 66,465 households; net geometric mean |
| Average household gross return | 18.7% annualized | 66,465 households; gross geometric mean |
| Fama-French net spread Q5 − Q1 | −80 bp/month (−9.6%/year) | t=−4.59; Table V, high minus low turnover quintile |
| Market-adjusted net spread Q5 − Q1 | −46 bp/month (−5.5%/year) | t=−1.56; Table V, high minus low turnover quintile |
| Average annual portfolio turnover | >75% | Average household; common stocks only |
| Round-trip transaction cost (>$1,000) | ~4% (~3% commissions + ~1% bid-ask) | Section II.A; trade-weighted average |
| Households outperforming market after costs | 43.4% | Table IV; 62,439 households with >12 months of data |
| Tax-deferred account annual turnover | 67.6% | Table VI; monthly turnover 5.63% × 12 |
| Taxable account annual turnover | 89.4% | Table VI; monthly turnover 7.45% × 12 |

## Why This Matters

The finding contradicts the Grossman-Stiglitz rational model, which predicts active traders earn higher gross returns to offset transaction costs. Behavioral finance models incorporating overconfidence generate a stronger prediction: active strategies will underperform passive ones, not merely match them. Overconfidence is the authors' preferred mechanism: investors overestimate the value of their private information and trade too actively as a result. Individual trading costs exceed mutual fund costs because households execute small trades at retail commission rates. Trade count is the variable this study isolates, and it is the one most traders never measure. A [trading journal](/trading-journal/) totals it alongside net return so the relationship shows up in your own data.

## FAQ

### What does Barber and Odean (2000) show about active individual investor returns?

11.4 percent versus 17.9 percent: those are the net annual return for the most active quintile and the market. The least active quintile earns 18.5 percent net annually—7.1 percentage points more than the most active quintile. Barber and Odean analyze 66,465 households at a large U.S. discount broker from 1991 to 1996.

### How large are the transaction costs individual investors face?

4 percent: the approximate round-trip transaction cost per trade over $1,000—about 3 percent in commissions and 1 percent in bid-ask spread. The average purchase incurred a 0.31 percent spread; the average sale, 0.69 percent. Transaction costs, not poor stock selection, explain the underperformance of individual investors.

### How does the overconfidence model compare to the rational expectations model?

80 basis points per month: the Fama-French net return spread between the most and least active turnover quintiles (t=−4.59, or 9.6 percent per year). Overconfidence models predict that investors who trade more earn lower net returns. The Grossman-Stiglitz rational model predicts no such difference in net returns across turnover groups.

### Does tax-loss selling or rebalancing explain the high trading volume?

67.6 percent annual turnover was recorded in tax-deferred IRA and Keogh accounts. Tax-loss selling provides no benefit there, yet turnover nearly matched the 89.4 percent in taxable accounts. With an average of 4.3 stocks per household, risk-based rebalancing cannot account for the observed 75 percent annual turnover, the authors argue.

## Source

Barber, B. M. and Odean, T. (2000). Trading Is Hazardous to Your Wealth: The Common Stock Investment Performance of Individual Investors. *Journal of Finance*, 55(2), 773–806.

[Read the full paper →](https://faculty.haas.berkeley.edu/odean/papers%20current%20versions/Individual_Investor_Performance_Final.pdf)