Individual Investors Lose 3.8 Percentage Points Annually to Active Trading
Active retail trading imposes systematic, economically large costs on individual investors. Turnover on the Taiwan Stock Exchange averaged nearly 300% annually—two to three times U.S. rates during the same period. Barber, Lee, Liu, and Odean (2009), in "Just How Much Do Individual Investors Lose by Trading?", studied 3.9 million investors from 1995 to 1999. The aggregate individual investor portfolio lost 3.8 percentage points in annual return; total losses of $NT 935 billion equaled 2.2% of Taiwan's GDP.
What the Study Found
Individual investors lost $NT 35.3 million daily at a one-day horizon and $NT 178.7 million daily at a 140-day horizon. Of all trades, 64% emanated from aggressive orders, and virtually all individual investor losses traced to those aggressive trades. Passive individual trades generated short-run profits that eroded to zero by 25 to 140 trading days. Institutions earned annual abnormal returns of 1.5 percentage points after commissions and transaction taxes. Foreign institutions captured 46.2% of total institutional trading and market-timing gross profits at a six-month horizon.
Methodology
The dataset is the complete Taiwan Stock Exchange transaction history from January 1, 1995 through December 31, 1999. The sample included approximately 3.9 million individual investors, 24,000 corporations, 83 dealers, 1,600 foreigners, and 289 mutual funds. Dollar profits used calendar-time portfolios mimicking net daily purchases and sales at holding periods of 1, 10, 25, and 140 trading days. Abnormal returns were estimated with a four-factor model controlling for market, size (SMB), value (HML), and momentum (WML).
Key Statistics
| Metric | Finding | Context |
|---|---|---|
| Annual return penalty for individual investors | 3.8 percentage points | Aggregate individual portfolio, Taiwan Stock Exchange 1995–1999 |
| Total individual investor losses | $NT 935 billion ($US 32 billion) | Taiwan Stock Exchange, 1995–1999 |
| Annual individual investor losses | $NT 187 billion ($US 6.4 billion) | Average per year, Taiwan Stock Exchange 1995–1999 |
| Losses as % of Taiwan GDP | 2.2% | Five-year total 1995–1999 |
| Losses as % of total personal income | 2.8% | Five-year total 1995–1999 |
| Loss breakdown: trading losses | 27% of total | Taiwan Stock Exchange 1995–1999 |
| Loss breakdown: commissions | 32% of total | Taiwan Stock Exchange 1995–1999 |
| Loss breakdown: transaction taxes | 34% of total | Taiwan Stock Exchange 1995–1999 |
| Loss breakdown: market-timing losses | 7% of total | Taiwan Stock Exchange 1995–1999 |
| Annual institutional gain (after transaction costs) | 1.5 percentage points | Aggregate institutional portfolio, Taiwan Stock Exchange 1995–1999 |
| Foreign institutions' share of institutional profits | 46.2% | Trading and market-timing gross profits, six-month horizon |
| Mean daily individual losses (140-day horizon) | $NT 178.7 million | t = −4.68; Taiwan Stock Exchange 1995–1999 |
| Share of trades from aggressive orders | 64% | All trades, Taiwan Stock Exchange 1995–1999 |
| TSE annual turnover | approximately 300% | Average 1995–1999 |
| Day trading as % of total trading volume | 23% | By dollar value, Taiwan Stock Exchange 1995–1999 |
| Four-factor model | Rt − Rft = α + β(Rmt − Rft) + s·SMBt + h·HMLt + w·WMLt | Monthly abnormal return estimation for each investor group (Equation 1) |
| Cumulative Abnormal Return | CART = Σ(MAbuy_τ − MAsell_τ) | Event-time return on stocks bought less stocks sold (Equation 2) |
Why This Matters
Countries relying on personal investment accounts for retirement savings expose citizens to the costs of uninformed active trading. Taiwan equity mutual funds earned positive net returns despite annual expense ratios of 2.4% to 3.1%. Fewer than 1% of household equity was held in funds during the sample period, suggesting most investors did not take the lower-cost alternative. The lottery experiment implies that some retail trading serves a gambling motive, complicating purely educational responses to overtrading.