Guide · Asset Allocation
Best one-fund portfolio ETFs
An all-in-one allocation ETF is a fund that holds other index funds — a fixed global stock/bond mix maintained inside a single ticker. The iShares Core Allocation series covers four splits: AOA at 80/20 stocks/bonds, AOR at 60/40, AOM at 40/60, and AOK at 30/70. Each holds the same seven underlying iShares Core ETFs (S&P 500, mid- and small-cap, international developed, emerging markets, and US and international broad bond funds) and rebalances back to its target internally. It is a 3-fund portfolio's diversification with zero maintenance, priced at 0.15% instead of the ~0.03–0.04% the parts cost separately.
How the scoring ranks these funds
The four iShares funds carry the same 0.15% expense ratio and the same fund-of-funds structure, so their ordering is driven almost entirely by liquidity (AUM) and tax efficiency. The fifth fund on the board, CGBL, is Capital Group's actively managed core balanced ETF at 0.33% — a manager-run 60/40 rather than a fixed-split index wrapper. The equity-heavier funds distribute less ordinary income, but the two middle splits have attracted the most assets — AOR's size edge over AOA is what puts it first despite AOA's slightly better tax-efficiency sub-score. The concentration sub-score is N/A for the whole category (see the closing note), and the weights renormalize over the sub-scores that remain.
See the methodology for the full formula behind each sub-score.
Top picks
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81
composite / 100
The 60/40 fund — the textbook balanced allocation — and the largest of the series at ~$3.7B. Holdings are roughly one-third S&P 500, one-third broad US bonds, with international equity and bonds filling out the rest. The closest single-ticker stand-in for a moderate 3-fund portfolio.
- Expense
- 0.15%
- AUM
- $3.67B
- Issuer
- iShares
- Detail
- AOR page →
-
80
composite / 100
The 80/20 fund, equity-heaviest of the series. Lowest trailing yield of the four (2.1% TTM) because bond interest is the smallest slice, which is also why it posts the best tax-efficiency sub-score in the category.
- Expense
- 0.15%
- AUM
- $3.21B
- Issuer
- iShares
- Detail
- AOA page →
-
77
composite / 100
The 40/60 fund — the first of the series where bonds are the majority, with roughly half the portfolio in a single broad US bond fund. The conventional bond-majority point in a target-risk lineup.
- Expense
- 0.15%
- AUM
- $1.79B
- Issuer
- iShares
- Detail
- AOM page →
-
72
composite / 100
The 30/70 fund, most conservative and smallest (~$800M AUM). Highest trailing yield of the series (3.2% TTM), nearly all of it bond interest taxed as ordinary income — the tax-placement note below applies most strongly here.
- Expense
- 0.15%
- AUM
- $812.9M
- Issuer
- iShares
- Detail
- AOK page →
Also in the category
Other funds in the same category, ranked by composite score.
Why the concentration sub-score reads N/A
On paper these funds are maximally concentrated — seven holdings making up ~99.9% of assets. But each holding is itself a broad index fund, so a top-10 concentration figure measures the wrapper, not the exposure: AOR's look-through portfolio spans thousands of stocks and bonds. The PlainIndex methodology drops the concentration sub-score for fund-of-funds rather than report a misleading number, and renormalizes the composite over the sub-scores that remain.
The expense layering question
A fund that holds funds raises the obvious question of whether fees stack — the wrapper's fee on top of the underlying funds' fees. The cleaner way to evaluate it is the all-in comparison: each AO fund costs 0.15% per year, while assembling the same split from 3-fund building blocks (VTI at 0.03%, VXUS at 0.05%, BND at 0.03%) blends to roughly 0.03–0.04%. The ~11 basis-point gap is the price of automatic rebalancing and one-ticker simplicity; on a $100,000 balance that is about $110 per year.
Versus assembling the 3-fund yourself
The look-through exposure of AOR is close to the moderate age-50 mix on the 3-Fund Portfolio page. The DIY version is cheaper and allows asset-location choices a fixed-split wrapper cannot — bond income held in tax-advantaged accounts while equity sits in taxable. The all-in-one version never drifts, never tempts a rebalancing decision in a drawdown, and is one line on a statement. One structural point in the wrapper's favor: rebalancing happens inside the fund, where ETF in-kind mechanics can absorb much of it — though the AO funds have paid capital-gains distributions in some years, so the advantage is partial, not absolute. Rebalancing a DIY portfolio in a taxable account, by contrast, always realizes gains directly.
Tax placement
The bond-heavier funds in this series throw off 2.5–3.3% in distributions, most of it ordinary-income bond interest that cannot be split out and sheltered separately. In a tax-advantaged account (IRA, 401k) the distribution profile has no current-year tax impact. In a taxable account, the same split assembled from separate funds — bonds in the tax-advantaged account, equity in taxable — is structurally more tax-efficient than any single fixed-split wrapper can be.
Common questions
- Do these funds rebalance automatically?
- Yes — that is the product. Each fund maintains its target stock/bond split internally by tracking an S&P Target Risk index, so the 60/40 in AOR stays 60/40 without any action by the holder. The split is fixed, though: unlike a target-date fund, an AO fund never glides toward more bonds over time. Moving from AOA to AOR is a sale and a purchase, with the usual tax consequences in a taxable account.
- What is actually inside them?
- The same seven iShares Core ETFs: the S&P 500 fund plus mid- and small-cap funds for US equity, developed and emerging international equity funds, and broad US and international bond funds. The four AO funds hold the same components at different weights — only the stock/bond ratio changes across the series. (AOA also carries a residual S&P 500 futures position at ~0% weight.)
Guide. Picks come from the live PlainIndex composite for this category; editorial commentary on each pick is hand-written. Re-pulled with every catalog refresh.
PlainIndex publishes data and editorial commentary — nothing here is personalized investment advice. Read the methodology for how the scores referenced here are computed.