- Barber and Odean studied 66,465 households at a large discount broker (1991–1996): those that traded most earned 11.4% a year while the market returned 17.9%; the average household earned 16.4% and turned over 75% of its portfolio annually.
- The authors explain the pattern with overconfidence, and test it on 35,000 households: men traded 45% more than women, and trading cost men 2.65 percentage points a year against 1.72 for women.
- Every trade has a price: fees, spread and slippage. At leverage the same fee is a larger share of your own capital, so cost per trade matters more in crypto perpetuals than in unleveraged stocks.
- A cap on trades per day, set in advance, turns overtrading from a mood into a rule.
Overtrading is taking more trades than your edge can pay for. It is rarely a dramatic mistake. It is ten small entries a day, each “reasonable”, that add up to a worse result than three planned ones. A famous study of real accounts puts numbers on it.
What 66,465 households show
Barber and Odean examined 66,465 households with accounts at a large discount broker from 1991 to 1996. Their finding, in the abstract: “individual investors who hold common stocks directly pay a tremendous performance penalty for active trading”. Households that traded most “earn an annual return of 11.4 percent, while the market returns 17.9 percent”. The average household earned 16.4% and “turns over 75 percent of its portfolio annually”. The authors’ explanation: “Overconfidence can explain high trading levels and the resulting poor performance of individual investors.”1
The title of the paper says it directly: “Trading Is Hazardous to Your Wealth”.
Overconfidence, tested
If overconfidence drives excess trading, a group that is more overconfident should trade more. In a follow-up on more than 35,000 households (1991–1997), Barber and Odean sorted investors by gender, because “psychological research demonstrates that, in areas such as finance, men are more overconfident than women”. They found that “men trade 45 percent more than women”, and that “trading reduces men’s net returns by 2.65 percentage points a year as opposed to 1.72 percentage points for women”.2
The point is not about gender. It is that the more people trade, the more it costs them, and that the pull to trade more is linked to how sure they feel.
What these studies do not cover
Both studies are about common stocks held in brokerage accounts in the 1990s. They do not measure crypto perpetuals, 24-hour markets or leverage. Their lesson is the direction, not the size: more trading, with the same skill, costs more. The size for your own account you can compute.
The cost of one more trade
Every trade pays a fee and the spread and slippage (see slippage and price impact). A worked example with assumed numbers, not a quote from any exchange:
- a round-trip fee of 0.08% of position size (an illustration; real fees depend on your tier);
- 5x leverage, so the position is five times your margin;
- cost per trade = 0.08% × 5 = 0.4% of the margin;
- five trades a day = 2% of the margin a day, before any losing trade.
Twenty trading days at that pace is 40% of the margin spent on fees alone. A strategy needs to earn this back before it earns anything. This is why a rule on the number of trades is a risk rule, not a mood.
Why people overtrade
Three common triggers (our reading, not findings of the studies above):
- Boredom or the wish to be “in the game”. A quiet market feels like wasted time.
- A recent win that raises confidence in the next entry.
- A recent loss that raises the urge to repair it, which is revenge trading.
How to stop overtrading
- Set a maximum number of trades per day. For example three. When the counter is full the session is over.
- Define your setups in writing. If it is not on the list, it is not a trade.
- Count costs weekly. Add up fees and funding and compare them with the result. If costs are a large share of gross profit, you trade too often.
- Put a quiet-market rule in the plan. “If there is no setup by 14:00, I close the platform.”
- Review the trades you took outside the plan separately from the rest.
Free tools: the overtrading page shows how many trades and how many rule breaks you recorded and compares them; boredom trading and can’t stop for today give a protocol for those moments; and session and plan lets you set a trade cap that blocks the entry form once reached. Data stays in your browser.
Questions traders ask
How many trades a day is too many? There is no universal number. Compare your result with and without the trades outside your plan, and remember that costs rise with every trade.
Does overtrading only affect beginners? The studies analyse the general population of individual investors. Cost per trade is arithmetic and applies to anyone.
Is it overtrading if my system produces many signals? Not if each trade meets your written rules and your edge covers the costs. Check that by testing, not by feeling: see why backtests mislead.
Educational material, not investment advice. More in the Trading psychology category.
Footnotes
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Barber, B. M., Odean, T. “Trading Is Hazardous to Your Wealth: The Common Stock Investment Performance of Individual Investors”, The Journal of Finance 55(2), 2000. Quotations are from the abstract. ↩
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Barber, B. M., Odean, T. “Boys will be Boys: Gender, Overconfidence, and Common Stock Investment”, The Quarterly Journal of Economics 116(1), 2001. Quotations and figures are from the abstract (RePEc record). ↩
Sources
- Trading Is Hazardous to Your Wealth: The Common Stock Investment Performance of Individual Investors. Brad M. Barber, Terrance Odean. The Journal of Finance 55(2), 773–806, 2000
- Boys will be Boys: Gender, Overconfidence, and Common Stock Investment. Brad M. Barber, Terrance Odean. The Quarterly Journal of Economics 116(1), 261–292, 2001
This article is research, not investment advice. Results on history do not guarantee future results.