What a Three-Fund Portfolio Is Built On

A three-fund portfolio is built on three broad index funds: one holding the whole US stock market, one holding stocks from the rest of the world, and one holding US investment-grade bonds. Between them, the two stock funds cover most of the world's investable stock market value, and the bond fund adds a US-dollar fixed-income layer. The only inputs left to the investor are the split between the three and the rule for putting it back in line.

Key takeaways

As of June 30, 2026, the three Vanguard ETFs used here as illustrations tracked indexes with 3,482 US stocks, 8,579 non-US stocks and 14,173 US bonds, at expense ratios of 0.03%, 0.05% and 0.03%.
The MSCI ACWI IMI, a global stock index, had 62.99% of its weight in US companies on September 30, 2026, so a mix that is 71.4% US within its stock portion leans toward the US relative to world market weights.
The bond fund's index excludes inflation-protected (TIPS) and tax-exempt bonds, and all bonds are US dollar-denominated, so the mix has no inflation-linked or foreign-currency bond exposure.
In the worked example, an illustrative 60/24/16 mix costs about $34.80 a year per $100,000 and drifts by only 1.6 percentage points after a year of stated returns, so a 5-point band would call for no trade.

What each of the three funds covers

Each fund follows an index weighted by market capitalization, meaning each company or bond counts in proportion to its total market value. The funds do not choose among securities; they hold nearly all of them. The table uses Vanguard's ETF fact sheets as dated illustrations of what a broad-market fund holds. It does not recommend a provider, and other fund families publish comparable products with their own indexes.

Block (illustration)	Index tracked	Stated coverage	Securities, fund / index	Expense ratio
US stocks (VTI)	CRSP US Total Market (renamed Morningstar US Total Market on July 29, 2026)	About 100% of investable US companies	3,531 / 3,482	0.03%
International stocks (VXUS)	FTSE Global All Cap ex US	98% of non-US markets, developed and emerging	8,755 / 8,579	0.05%
US bonds (BND)	Bloomberg US Aggregate Float Adjusted	Investment-grade, taxable, US dollar-denominated, fixed-rate	11,476 / 14,173	0.03%

Figures as of June 30, 2026, from the Total Stock Market ETF, Total International Stock ETF and Total Bond Market ETF fact sheets. The expense ratios are those reported in the most recent prospectus and can change. After those fact sheets were dated, Morningstar's acquisition of CRSP led to a rebrand: Vanguard's prospectus supplement dated July 29, 2026 renamed the US index the Morningstar US Total Market Index and the fund Vanguard Morningstar Total Stock Market Index Fund, effective that day, and states that the fund's investment objective, strategies and policies are unchanged.

Why the fund holds a different count than its index

The counts do not match one for one, and the gap runs in different directions. The bond fund held 2,697 fewer bonds than its index (11,476 against 14,173). Its fact sheets say it uses index sampling, and the Admiral-share sheet explains that the fund holds a range of securities that, in the aggregate, approximate the full index in terms of key risk factors, rather than buying every issue. The two stock funds held slightly more names than their indexes: 49 more for US stocks (3,531 against 3,482) and 176 more for international stocks (8,755 against 8,579). The fact sheets do not explain the surplus, so the practical point is narrower: a fund's holdings track its index closely but are not an exact copy, and the index count is the better guide to what the strategy covers.

How concentrated each block is

The ten largest holdings made up 33.4% of the US stock fund and 15.0% of the international stock fund, according to the same June 2026 fact sheets. Broad coverage does not mean equal weights: market-cap weighting lets a handful of very large companies drive much of a US index's movement. The international fund's largest country allocation, Japan, was 15.4% of its common stock.

How much of the world the US represents

The split between the two stock funds is where the portfolio takes a position on geography. The MSCI ACWI IMI factsheet, a global index of large-, mid- and small-cap stocks in 23 developed and 24 emerging markets, listed 8,036 constituents covering roughly 99% of the global investable equity opportunity set, with the United States at 62.99% as of September 30, 2026. MSCI and FTSE measure the world differently, so the exact share varies by index provider and by date; the factsheet is updated monthly, so the link will show newer figures over time.

What the three funds leave out

Three broad funds are not a complete portfolio. Four gaps matter when reading the mix.

Inflation-linked bonds. The bond fund's stated approach is exposure to the US bond market "excluding inflation-protected and tax-exempt bonds." Treasury Inflation-Protected Securities (TIPS) work differently from the fixed-rate bonds in the index: TreasuryDirect states that a TIPS principal rises with inflation and falls with deflation, interest is paid on the adjusted principal, and at maturity the holder never receives less than the original principal. A fixed-rate bond pays set dollar amounts that inflation erodes in purchasing power.
Non-dollar bonds. The index is US dollar-denominated. A small slice of issuers is foreign (3.5% of the bond fund's distribution by issuer at June 30, 2026), but the bonds are still dollar-denominated, so there is no bond exposure in other currencies. Direct currency exposure enters only through the international stock fund, whose fact sheet lists currency risk among the risks of non-US stocks.
Cash. None of the three is a cash reserve. Money for near-term spending needs sits outside the mix.
Direct real estate and commodities. Real estate appears only as a sector inside stock indexes: 2.3% of the Total Stock Market fund's sector breakdown at June 30, 2026, and 2.08% of the MSCI ACWI IMI at September 30, 2026.

Small and mid-sized companies are not left out. The US index includes large-, mid-, small- and micro-cap stocks, and the international index is an "all cap" index. Both reach well beyond the large companies in headline indexes.

How the three combine into a mix

The two stock funds together represent the stock side, and the bond fund the bond side. The first choice is the stock-to-bond split. This article takes the weights as given and looks at how the pieces fit. The second choice is how to divide the stock side between US and non-US funds.

The weights below are illustrative, chosen for arithmetic clarity. They are not a recommended allocation.

Block	Illustrative weight	Share of the stock side
US stocks	60%	71.4% (60 / 84)
International stocks	24%	28.6% (24 / 84)
US bonds	16%	not applicable

Compared with the 62.99% US weight in the MSCI index, a 71.4% share of the stock side is a deliberate tilt toward the home market. The US-only bond block adds a second home-market lean that the stock split does not show. Neither tilt is an error; both are decisions that should be made knowingly rather than by default.

How a rebalancing band works

A band is a stated amount of drift that triggers a trade. With a 5-percentage-point band, a block with a 60% target is left alone while it sits between 55% and 65%, and rebalanced once it moves outside. The band is checked at set dates, such as once a year. The SEC's investor education office lists three ways to rebalance: sell holdings that have grown overweight and buy those that are underweight, buy more of the underweight holdings, or direct new contributions to the underweight categories. It also notes that selling securities can trigger capital gains or other taxes. How often to check is a trade-off between trading costs, taxes and risk control; the band is only one of several workable rules.

Worked example: cost and drift

Illustrative example. A $100,000 portfolio holds the 60/24/16 mix above in the three ETFs from the table. All returns are stated assumptions for the arithmetic, not forecasts, and they ignore the fund's own expenses and taxes.

Blended expense ratio

blended ratio = sum(weight_i x expense ratio_i)
              = 0.60 x 0.03% + 0.24 x 0.05% + 0.16 x 0.03%
              = 0.0180% + 0.0120% + 0.0048%
              = 0.0348% a year

Here weight_i is each fund's share of the portfolio and expense ratio_i is its annual cost as a percentage of assets. On $100,000, 0.0348% is $34.80 a year. A single fund charging 1% would cost $1,000, which is 28.7 times as much. Expense ratios vary by share class: the Admiral mutual fund share classes of the same three Vanguard funds report 0.04%, 0.09% and 0.04% on June 2026 fact sheets for the US stock, international stock and bond funds. The same weights give a 0.052% blend, or $52 a year.

Scenario A: returns close together

Assume one year of stated returns of +12% for US stocks, +6% for international stocks and +3% for bonds.

Block	Start	Year-end value	Year-end weight	Drift vs target	Trade to rebalance
US stocks	$60,000	$67,200	61.58%	+1.58 points	Sell $1,728.00
International stocks	$24,000	$25,440	23.31%	-0.69 points	Buy $748.80
US bonds	$16,000	$16,480	15.10%	-0.90 points	Buy $979.20
Total	$100,000	$109,120	100%		$0 net

The portfolio gained 9.12%. Every block ends inside a 5-point band, so a band rule calls for no trade; a strict return-to-target rule would sell $1,728.00 of US stocks, 1.6% of the portfolio, and buy $748.80 of international stocks and $979.20 of bonds. The drift is small because the three stated returns were close together. Another way to restore the mix without selling is to add $2,880 of new money: $1,440 to international stocks and $1,440 to bonds brings every block to its target weight on a $112,000 total.

Scenario B: a wider spread

Now assume +25% for US stocks, +5% for international stocks and -8% for bonds. The year-end values are $75,000, $25,200 and $14,720, for a total of $114,920 (a gain of 14.92%). US stocks reach 65.26% of the portfolio (+5.26 points), international stocks fall to 21.93% (-2.07 points) and bonds to 12.81% (-3.19 points). US stocks have moved outside the 5-point band, so the rule triggers: sell $6,048.00 of US stocks and buy $2,380.80 of international stocks and $3,667.20 of bonds. The trades net to zero.

The two scenarios show that a band rule does nothing when the blocks' returns are close together and acts when one block pulls well ahead. They also show why a taxable account needs attention: selling $6,048.00 of a block that rose 25% may realize a gain, which the SEC bulletin above flags as a consideration.

Frequently asked questions

Can the same three exposures come as mutual funds instead of ETFs?

Yes. Some fund companies offer the same index fund in both forms; Vanguard's July 2026 prospectus supplement, for example, lists Vanguard Morningstar Total Stock Market ETF as the ETF share class of the renamed Total Stock Market Index Fund. The difference is how they trade: the SEC's Investor.gov says a mutual fund order is priced at the end of the business day, while ETF shares trade on an exchange at prevailing market prices throughout the day. Costs differ by share class, as the 0.04%, 0.09% and 0.04% Admiral figures above show.

Does the bond fund hold any foreign bonds?

The index holds only US dollar-denominated bonds, but some issuers are foreign. Vanguard's June 30, 2026 fact sheets list "Foreign" at 3.5% of the distribution by issuer, and the Admiral-share sheet describes the index as including international dollar-denominated bonds. There is no exposure to bonds that pay in other currencies.

Is the international fund only developed markets?

No. The index covers developed and emerging markets outside the United States. The June 30, 2026 country breakdown on the fund's fact sheet includes Taiwan at 9.1%, Korea at 7.5%, China at 6.7% and India at 4.4% of common stock, alongside Japan, the United Kingdom and Canada.

How often do the three funds pay out income?

The ETF fact sheets for June 30, 2026 list a quarterly dividend schedule for the US stock and international stock funds and a monthly schedule for the bond fund. Payouts that are spent rather than reinvested leave the portfolio, so they also move the weights.

Did the US stock index change its name?

Yes. After Morningstar acquired CRSP, the CRSP US Total Market Index became the Morningstar US Total Market Index, and the fund became Vanguard Morningstar Total Stock Market Index Fund, with the ETF class renamed Vanguard Morningstar Total Stock Market ETF. Vanguard's prospectus supplement gives July 29, 2026 as the effective date and says the fund's objective, strategies and policies are unchanged. Fact sheets dated June 30, 2026, like those used here, still show the CRSP name, so older and newer documents use different names for the same index.

A checklist before building the mix

Open each fund's own fact sheet, whichever provider offers it, and note the as-of date, the index it tracks, the number of securities and the expense ratio.
Confirm what the bond index excludes (TIPS, tax-exempt bonds) and whether that matches how the money will be used.
Write down the stock/bond split and the US/international split, then compare the US share of the stock side with a global index's current figure.
Compute the blended expense ratio: multiply each weight by its expense ratio and add the results.
Decide in advance when to check the mix and how large a drift triggers a trade. The Rebalancing Calculator on this site shows the trade amounts for any set of weights and values.
Before selling in a taxable account, compare the trade with the option of directing new money to the underweight blocks.