Pro Investor Academy
LESSON 3.3
6 min learning time

Costs and Expense Ratios

Small annual fees compound into large amounts over decades.

The short answer

An expense ratio is an annual percentage of your fund balance deducted automatically to pay for running the fund, and because it is charged every year on a growing balance, even a fraction of a percent compounds into a substantial share of your final wealth over decades. Comparing expense ratios before comparing past returns is one of the few genuinely reliable ways to improve a long-term outcome.

Learning objectives

  • Calculate the annual dollar cost of a given expense ratio on a balance
  • Explain why a fee charged as a percentage compounds against you over time
  • Identify the other costs that sit alongside the expense ratio

How the fee is charged

An expense ratio is an annual percentage taken from fund assets. A 0.60% ratio costs $6 per $1,000 per year, deducted quietly from the fund's assets rather than billed to you directly.

Why a fraction of a percent matters

Fees are charged on the entire balance every year, including growth. Over decades, the difference between 0.05% and 0.75% compounds into a meaningful share of the final balance, because the fee itself never gets the chance to compound on your side of the ledger.

Vanguard's research on active management makes the same point from another direction: costs and discipline matter more than timing.

A hypothetical illustration

This is hypothetical arithmetic, not a projection. Two identical $10,000 investments growing at the same assumed 7% annual rate before fees, held for 30 years, would separate meaningfully once one is reduced by a 0.05% expense ratio and the other by a 0.75% expense ratio — purely because of the fee difference compounding each year. The exact endpoint numbers depend on assumptions that never hold exactly in reality; the direction and scale of the effect is the lesson, not any specific figure.

Other costs to check

Beyond the expense ratio:

  • Bid-ask spread on thinly traded funds
  • Trading commissions, where they still apply
  • Sales loads on some mutual funds
  • Advisory fees layered on top of fund fees
What a fee actually is
Low-cost fund0.03%–0.10% typical for broad index ETFs

Charged annually on assets

Higher-cost fund0.50%–1.00%+ typical for many active funds

Same mechanism, larger drag

What it buysFund administration, index licensing, management

Not a guarantee of better results

An expense ratio is charged on the whole balance every year, so it compounds in the fund's favour just as returns compound in yours.

Key concepts

Select a term to read its definition.

See the full glossary

Why this matters

Fees are the one variable you fully control before you ever pick an investment.

Common mistakes

  • Comparing two funds by past performance while ignoring a 10x difference in fees.

Check your understanding

No score is recorded. This is only here to test whether the lesson landed.

1. How is an expense ratio charged?
2. True or false: a 0.05% difference in expense ratio can compound into a meaningful cost difference over a long holding period.
3. Two hypothetical funds track the same index with similar holdings, but one charges 0.03% and the other charges 0.65%. All else being roughly equal, what does this level's material suggest?

0 of 3 answered. Answer every question to see the answers.

Key takeaways

  • An expense ratio is a percentage of assets charged every year, not a one-off fee
  • Because it compounds annually on a growing balance, a small percentage difference becomes large over decades
  • Bid-ask spreads, loads and advisory fees can add to the cost beyond the expense ratio
  • Cost is observable in advance; future performance is not

Related concepts

Written by
Pro Investor Academy Research Team
Content type
Educational article
Published
2026-09-13
Last reviewed
2026-09-13

Sources

Index InvestingETF Diversification

Educational content only. This lesson is not investment, tax or legal advice and does not recommend buying or selling any specific investment. All investing involves the risk of loss.