Overtrading
Also known as: Excessive trading
The more people trade, the lower their returns — yet they keep trading.
What it means
The tendency of investors to buy and sell far more frequently than is in their interest, eroding returns through transaction costs and poorly timed switches. The chief culprit is overconfidence: traders overrate the precision of their information and their ability to beat the market, so they trade on noise. Studies show the most active retail traders earn the lowest net returns, and that men, who are typically more overconfident, trade more and lose more than women. It matters because overtrading is a direct, costly bridge from a psychological bias to measurable wealth destruction.
Examples
A retail trader who churns his account chasing tips ends the year well behind a buy-and-hold investor in the same stocks.
Studies of thousands of brokerage accounts find that the most active households badly underperform the least active ones, though both hold broadly similar shares. The gap is almost entirely the trading itself.
An app that puts the buy button one thumb-tap away and throws confetti at every fill turns a five-times-a-year investor into a five-times-a-week one. Fees and spreads quietly take the difference.
First described in Odean (1999); Barber & Odean (2000, 2001).