Investing

Index funds vs. ETFs: which should you use?

They're two wrappers around almost the same idea. Here's the honest difference — and why, for most long-term investors, it matters far less than the fee.

First, what they have in common

Both an index fund and an ETF can hold every company in a market index — like the S&P 500 — in a single, broadly diversified basket. Buy one share and you own a slice of hundreds of companies. That diversification, at a low cost, is the part that actually builds wealth, and both deliver it.

How they actually differ

An index fund (technically a mutual fund) is priced once a day, after the market closes, and you buy it in dollar amounts — great for automatic recurring investing. An ETF trades like a stock throughout the day, is usually easy to buy in fractional shares, often has no minimum, and is typically a touch more tax-efficient in a regular taxable account. Inside a retirement account, that tax difference mostly disappears.

Which one to choose

For most people investing for the long term, either is a fine choice — so don't overthink it. Compare the expense ratio first (lower is almost always better), then pick the format that fits how you invest: index funds for simple, set-and-forget automatic contributions; ETFs for flexibility and fractional buying. The worst choice is neither — it's waiting.

Where to buy them

You buy both inside a brokerage account. If you don't have one yet, opening a brokerage account is the first practical step — most major brokers offer their own low-cost index funds and ETFs with no commission.