3-Fund Portfolio: A Simple Investing Strategy
What the three-fund portfolio is, which index funds and ETFs fill each slot, sample allocations by age and risk, what it costs, how to rebalance and how it compares with target-date funds.
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Key takeaways
- Three funds: a U.S. total stock market fund, a total international stock fund and a total bond market fund.
- Together they hold thousands of stocks and bonds worldwide, often for a blended cost of about 0.03% to 0.04% a year with the largest ETFs.
- The only real decision is the mix: how much in stocks versus bonds, and how much of the stock portion abroad.
- Rebalance once a year or when the mix drifts by more than about five percentage points.
The three-fund portfolio is the simplest serious way to invest for the long term. Popularized by the Bogleheads community of followers of Vanguard founder John Bogle, it replaces stock picking and complex fund menus with three broad index funds. You get global diversification, very low costs and a strategy that takes an hour a year to maintain.
The three funds
| Slot | What it holds | Example ETFs (expense ratio) |
|---|---|---|
| U.S. total stock market | Nearly every listed U.S. company, large to small | Vanguard VTI (0.03%), Schwab SCHB, iShares ITOT |
| Total international stock | Developed and emerging markets outside the U.S. | Vanguard VXUS (0.05%), iShares IXUS |
| Total U.S. bond market | Investment-grade government and corporate bonds | Vanguard BND (0.03%), iShares AGG |
Expense ratios change over time; check the fund's page before you buy. Equivalent mutual funds and funds from other providers work just as well, and many 401(k) plans offer similar index funds. For the difference between the wrappers, see ETF vs. mutual fund; for single-fund choices, best ETFs to buy.
Sample allocations
| Investor | U.S. stocks | International stocks | Bonds | Blended cost with the ETFs above |
|---|---|---|---|---|
| Aggressive, decades to retirement | 60% | 20% | 20% | about 0.034% |
| Growth, 40/40 stock split | 48% | 32% | 20% | about 0.036% |
| Moderate, approaching retirement | 36% | 24% | 40% | about 0.035% |
These are examples, not recommendations. A blended cost of 0.035% means about $3.50 a year per $10,000 invested.
Stocks vs. bonds
Stocks drive long-term growth but can fall 30% to 50% in a bad market; bonds grow more slowly but cushion those drops. A common starting point is to hold more stocks when retirement is far away and shift toward bonds as it approaches. Your own tolerance matters as much as your age: the right mix is one you will not abandon in a downturn. How to invest for retirement discusses allocation by age.
How much international
Companies outside the U.S. make up a large share of the world's stock market value. Many investors hold 20% to 40% of their stock portion internationally to diversify across economies and currencies. There is no single right answer; consistency matters more than the exact number.
How to build it
- Choose the account. Use tax-advantaged accounts first: a 401(k) with a match, then a Roth IRA or traditional IRA, then a taxable brokerage account.
- Pick your allocation and write it down.
- Buy the three funds in those proportions; fractional shares make exact percentages easy.
- Automate contributions and direct new money to whichever fund is below its target.
- Rebalance once a year or when a fund drifts more than about five percentage points from its target.
In taxable accounts, keep in mind that selling to rebalance can trigger capital gains tax; directing new contributions to the underweight fund avoids that. Where you hold bonds can matter too: interest is taxed as ordinary income, so many investors keep bonds in tax-advantaged accounts when possible.
Pros and cons
| Pros | Cons |
|---|---|
| Broad diversification across thousands of securities | No chance to beat the market; you earn market returns minus tiny costs |
| Very low costs | You must rebalance and adjust the mix yourself |
| Simple to understand and maintain | Bond funds can lose value when interest rates rise |
| Works in almost any brokerage or 401(k) | Requires discipline in bear markets |
Three-fund portfolio vs. target-date fund
A target-date fund packs a similar mix into one fund and shifts toward bonds automatically as the target year approaches. It is the easiest option, especially in a 401(k). The three-fund portfolio gives you more control over the mix and can be cheaper, at the cost of rebalancing yourself. Both are far better than a portfolio of hand-picked stocks for most people.
Frequently asked questions
Is a three-fund portfolio enough diversification?
Yes. Together the three funds hold thousands of U.S. and international stocks and investment-grade bonds.
What is the best three-fund portfolio allocation?
It depends on your time horizon and tolerance for losses. Common examples range from 80% stocks for young investors to around 60% or less for people near retirement.
How often should I rebalance?
Once a year is enough for most investors, or when an asset class drifts more than about five percentage points from its target.
Can I use a three-fund portfolio in my 401(k)?
Usually, if the plan offers a U.S. stock index fund, an international index fund and a bond index fund. If not, a target-date fund is a good substitute.
Should I use ETFs or mutual funds?
Either works. ETFs trade like stocks and are often more tax-efficient in taxable accounts; mutual funds allow automatic investing in exact dollar amounts at some brokerages.
