Index funds for FIRE: the simple portfolio behind early retirement

Why the FIRE movement runs on index funds

The FIRE movement is a compounding project: a high savings rate, invested for 15 to 30 years, growing into a portfolio of roughly 25 times your spending. Anything that quietly leaks a percent a year from that machine is a disaster in slow motion, and that is precisely what high-fee investing does. Fees compound exactly like returns do, just against you.

Index funds solve three problems at once. They cost almost nothing to hold. They guarantee you the market's return, which most professional stock pickers fail to beat over long periods after their own fees. And they demand no ongoing decisions, no forecasts, no trading, nothing to second-guess in a crash. For a plan measured in decades, that last part matters more than people expect.

What an index fund actually is

An index fund is a fund that skips the fund manager. Instead of paying a team to pick winners, it simply buys every company in a published list, an index, in proportion to size. A total US market fund holds thousands of American companies at once; a global fund holds most of the investable world. When you buy one unit, you buy a sliver of all of them.

Because nobody is being paid to make picks, the running cost, called the expense ratio, can be tiny, a few hundredths of a percent per year. Your return is the market's return minus that sliver. That's the whole product: maximum diversification, minimum cost, zero cleverness. It sounds like settling for average, but since most active funds trail the index they measure themselves against once fees are counted, buying the average is, over time, an above-average strategy.

The fee math: what 1% a year really costs

Here's the arithmetic, computed straight. Invest a lump sum at 7% a year for 30 years and it grows 7.61 times. Pay a 1% annual fee and you compound at 6% instead, growing 5.74 times. That gap is 24.5% of the final pot, roughly a quarter of your money, gone to a fee that sounded trivial. (If you're contributing monthly along the way rather than starting with a lump sum, the same 1% fee costs about 16% of the final pot, because later contributions have fewer years to be eroded. Still an enormous number.)

The difference between the 0.03% fund and the 1% fund is about $180,000 on a single $100,000 investment, for owning broadly the same assets. You cannot control what markets return, but the expense ratio is a return you lock in the day you choose the fund.

The classic simple portfolios

FIRE portfolios cluster around two patterns, both deliberately boring:

• The three-fund portfolio. A total domestic stock market fund, an international stock fund, and a bond fund. Three holdings cover essentially the entire investable world, and the only decision left is the split between them. Many people simplify further to two funds, or to a single global stock fund plus bonds.
• The one-fund approach. A target-date fund holds the whole mix inside one wrapper and gradually shifts from stocks toward bonds as your chosen year approaches. Slightly higher cost than assembling the pieces yourself, in exchange for never having to rebalance anything.

You'll also meet the phrase "VTSAX and chill", community shorthand for buying one total-market fund, VTSAX being a widely cited example of the type, and simply getting on with your life. Treat tickers like that as cultural references, not recommendations: the pattern, one broad cheap fund held for decades, is the point, and every major provider offers funds that fit it. Which mix suits you depends on your age, taxes and nerve, which is a decision for you or an advisor, not a web page.

Asset allocation by FIRE phase

The right stock/bond split changes with the job the portfolio is doing:

• Accumulating. Decades from withdrawal, volatility is noise and growth is everything, so allocations here are typically stock-heavy. A crash while you're still buying is arguably a discount.
• Coasting. Once you've hit your Coast FIRE number and stopped contributing, growth alone must carry the plan, so most coasters stay mostly in stocks while the runway is long, easing off as retirement approaches.
• Withdrawing. Now order of returns matters as much as average returns. A deep crash in the first few years of drawdown does far more damage than the same crash later, which is why retirees hold bigger bond and cash buffers. The mechanics are laid out in our guide to sequence of returns risk.

What index funds don't protect you from

Index funds remove single-company risk and manager risk. They remove nothing else. When the market falls 30%, your total-market fund falls right alongside it, diversification across thousands of companies is no defense against everything falling at once. Historically markets have recovered, but a plan built on the 4% rule still has to survive the trip, and a brutal sequence early in retirement can sink a portfolio that back-tested beautifully. Index funds are the cheapest, simplest vehicle for market returns; they are not a promise about what those returns will be. Your defenses are your allocation, your withdrawal rate and your flexibility, not the fund wrapper.

Frequently asked questions