Introduction: Why Beginners Lose Money
According to the annual DALBAR study, the average individual investor earns an annualised return of only 3.6% over 20 years, compared to 9.6% for the S&P 500 over the same period. This 6-point annual gap is not due to bad luck but to recurring behavioural mistakes that we will detail below. Knowing them allows you to avoid them.
Mistake 1: Trying to Time the Market
This is the most costly mistake. Market timing means trying to buy at the bottom and sell at the top. Yet no one -- not even professional fund managers -- can do this consistently.
A J.P. Morgan study shows that if you had missed the 10 best days of the S&P 500 over 20 years (out of approximately 5,000 trading days), your annualised return would have dropped from 9.4% to 5.2%. Missing the 20 best days reduces it to 2.8%. The problem? These best days often occur right after the worst ones, when panicked investors have already sold.
Solution: invest regularly via DCA (dollar-cost averaging) and stay invested no matter what.
Mistake 2: Not Diversifying Enough
Concentrating your portfolio on 3 or 4 individual stocks exposes you to enormous company-specific risk. A single piece of bad news (accounting fraud, lawsuit, contract loss) can send a stock down 50% or more in days.
Example: an investor who put all their capital into Orpea (a French care home operator) in 2021 saw their investment lose more than 90% of its value in 18 months following the scandal revealed in Victor Castanet's book.
Solution: a single MSCI World ETF diversifies you across more than 1,500 companies in 23 countries. It is the ultimate diversification in a single holding.
Mistake 3: Ignoring Fees
Fees are the only element you can control with certainty, and their impact is devastating over the long term. The difference between an actively managed fund at 2% annual fees and an ETF at 0.25% seems trivial, but over 30 years with a starting capital of 100,000 euros and a gross return of 8%:
- ETF at 0.25%: final capital of 935,000 euros
- Active fund at 2%: final capital of 574,000 euros
- Difference: 361,000 euros lost to fees
Solution: choose low-cost ETFs on a PEA (France's tax-advantaged equity savings plan). Avoid fee-laden bank products.
Mistake 4: Investing Without an Emergency Fund
Investing money in the stock market that you might need short-term is a recipe for disaster. If you must sell your shares urgently during a crash to cover an unexpected expense, you lock in your losses at the worst possible moment.
Solution: build an emergency fund of 3 to 6 months of expenses in a liquid savings account (Livret A, LDDS -- France's government-guaranteed tax-free savings accounts) before investing a single euro in the stock market.
Mistake 5: Panic-Selling During Downturns
Markets decline regularly. A 10% correction occurs roughly once a year, a 20% bear market roughly every 3-4 years, and a major crash of 40%+ roughly once a decade. This is normal and inevitable.
Selling in panic at the bottom of a decline is the worst possible decision. Historically, the market has always recovered to new highs after every crash (including after 2008 and 2020).
Solution: do not check your portfolio every day. Invest mechanically. Downturns are sales for the long-term investor.
Mistake 6: Following Fads and Hype
Obscure cryptocurrencies, meme stocks (GameStop, AMC), trendy thematic ETFs (hydrogen, metaverse, cannabis)... Beginner investors are drawn to assets that have already risen sharply, hoping the trend will continue.
Statistically, thematic ETFs launched at the peak of a trend underperform the MSCI World in 80% of cases over the following 5 years.
Solution: stick with broad, diversified indices. If an investment is making headlines, it is often too late.
Mistake 7: Not Using the PEA
Investing in ETFs on a CTO (standard brokerage account) while your PEA is not full is a pure tax mistake. As we have seen, the PEA's tax savings can represent tens of thousands of euros over 20 years. The PEA exempts capital gains from income tax after 5 years, leaving only 17.2% social contributions versus the 30% flat tax on a CTO.
Solution: open a PEA immediately to start the clock, even with just 10 euros. Fill it as a priority before using a CTO.
Mistake 8: Over-Trading
Frequent trading (multiple buys and sells) generates brokerage fees, spreads, and above all a tendency to make bad emotional decisions. Studies show that the more an investor trades, the worse they perform.
Solution: limit yourself to one order per month (your monthly DCA). The rest of the time, do not touch anything.
Mistake 9: Ignoring Your Time Horizon
The stock market is volatile in the short term but profitable over the long term. Over any 15-year period or longer, the MSCI World has never produced a negative return (with dividends reinvested). However, over a single year, the probability of loss is approximately 30%.
Solution: only invest in the stock market money that you will not need for at least 8 to 10 years.
Mistake 10: Not Starting Early Enough
Procrastination is perhaps the most costly mistake of all. Thanks to compound interest, every year of delay is expensive. Starting to invest 300 euros per month at 25 rather than at 35 could mean 200,000 euros more at 60 (at 8% annual return).
Solution: the best time to start was yesterday. The second-best time is now. Open your PEA, choose a World ETF, and launch your first DCA this month.