Don't Be Misled: Common Myths About Index Funds Debunked

Index funds are designed to replicate the performance of a specific market index, such as the S&P 500. They work by pooling money from multiple investors to purchase a diversified portfolio that mirrors the composition of the index it's tracking.

It's typically a passive investment that offers lower management fees than actively managed funds. Best of all, some funds -- like the Schwab S&P 500 Index Fund -- provide investors with broad market exposure, reducing portfolio risk through diversification.

As simple as the strategy is, there are common myths surrounding even the safest index fund investments -- falsehoods that could affect how you invest and whether you make the most of those investments. Here are three of the most common myths.

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Myth No. 1: Index funds are risk-free

If you ever hear that passive investing is without risk, you know it's a myth. A common misconception is that because index funds don't attempt to beat the market, they naturally avoid risk. Since index funds don't typically rely on a fund manager, they do sidestep the risk that the manager will underperform the benchmark. However, there's still market risk.

If the underlying market falls sharply, your index fund will fall with it, which means you still need a highly diversified portfolio and time on your side. An index fund is only as strong as the index it tracks, and the more unusual the index, the more closely it needs to be watched.

Myth No. 2: Index funds always lead to broad diversification

Index funds are indeed designed to provide diversification, but several factors may prevent that from happening. For example:

• Weighted market capitalization: Many indexes are weighted by market capitalization, meaning larger companies have greater influence on the index's performance. With that, an index fund could concentrate on a few large stocks, which reduces actual diversification.
• Sector concentration: Some index funds have high exposure to specific sectors, such as technology or real estate. Let's say you invest in the Vanguard Information Technology ETF, and the tech sector underperforms; the index fund's performance is likely to suffer, despite how "diversified" it appears.
• Geographic concentration: Funds that focus solely on specific regions or markets may lack the global diversification you seek. For example, if an index fund tracks a U.S. index, it can't benefit from international market growth.
• Limited holdings: Some indexes hold a limited number of stocks, and fewer holdings can increase risk if those stocks hit a rough patch simultaneously.

Myth No. 3: Passive investing means "set it and forget it"

One nice thing about investing in index funds is how little babysitting they require. Still, that doesn't mean you can purchase one and walk away. In practice, you'll still need to:

• Monitor asset allocation across stocks, bonds, and cash.
• Periodically rebalance your investments as markets move.
• Ensure that your portfolio doesn't drift away from your intended risk level.

There's no denying that index funds can be a great investment due to low fees, diversification, and a passive management approach. However, they still require an overall investment strategy and your touch to ensure they continue to meet your long-term goals.

Dana George has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.