Starting with index funds is simple — but a few common errors can cost you years of growth.
The good news about index fund investing is that it's genuinely simple. The bad news is that simple doesn't mean mistake-proof. Here are the five most common errors beginners make — and exactly how to avoid them.
This is the most costly mistake. New investors wait for a market dip, or worry the market is "too high," or plan to invest "when things settle down." The result: they stay in cash for months or years while the market climbs.
The research is clear: time in the market beats timing the market. A 2019 Charles Schwab study found that even investing at the worst possible time every year (right before major crashes) still significantly outperformed staying in cash over 20 years. Start now, with whatever amount you have.
Investing is great — but not if a car repair forces you to sell your index funds at a loss two months later. Before investing, build 3-6 months of expenses in a high-yield savings account. This prevents you from becoming a forced seller at the worst possible time.
Daily portfolio checking is one of the most documented causes of poor investment returns. Investors who check frequently are more likely to panic-sell during downturns and make emotional decisions. Set up automatic contributions, check quarterly for rebalancing, and otherwise leave it alone. The best investors are often those who forget their portfolio exists.
Beginners sometimes think more funds = more diversification. In reality, owning 10 different U.S. equity index funds is not meaningfully more diversified than owning one — they all track similar markets. One or two funds genuinely provides all the diversification most investors need. Complexity without benefit is just noise.
When the market drops 20-30%, the natural instinct is to stop investing — or worse, sell. But market downturns are exactly when index fund shares are cheapest. Continuing (or increasing) contributions during downturns is what dollar-cost averaging is designed for, and it's how long-term investors build the most wealth. Bear markets are a feature, not a bug.