Ideal Index Portfolio
The Ideal Index Portfolio was created by Frank Armstrong III, a financial advisor and founder of Investor Solutions, and introduced in his book The Informed Investor: A Hype-Free Guide to Constructing a Sound Financial Portfolio. The portfolio applies modern portfolio theory to a seven-fund index structure, with a 70% equity allocation and 30% short-term bonds. The equity sleeve has a strong value tilt and a heavy international weighting -- roughly half of equities are allocated to developed international stocks -- along with meaningful exposure to US REITs.
Investment Philosophy
Armstrong's approach draws on the academic evidence that certain risk factors -- particularly the size and value premiums documented by Fama and French -- can improve risk-adjusted returns when targeted systematically through index funds. Rather than simply holding the market-cap-weighted global market, the Ideal Index Portfolio overweights small-cap and value stocks within both the US and international sleeves. The short-term bond allocation is designed to anchor volatility without taking unnecessary interest rate risk. The premise is that smart asset class choices within a low-cost index framework can outperform both active management and simpler passive approaches over the long run.
Who It's For
This portfolio suits long-term investors who have absorbed the passive investing literature and want more than a plain three-fund approach. It is appropriate for investors comfortable with a value and small-cap tilt that may underperform the broad market for extended periods and who want meaningful international diversification.
Pros
- Grounded in peer-reviewed factor research rather than market-cap weighting alone
- Diversified across US equities, international equities, REITs, and short-term bonds
- Low-cost implementation using broad index funds in each asset class
Cons
- Strong value and small-cap tilts can lag the broad market for long stretches, testing investor patience
- Heavy international weighting has been a significant drag during periods of US equity dominance
- The seven-fund structure is more complex to maintain than a simple two- or three-fund portfolio
Technical Notes
Armstrong has periodically updated the portfolio's specific allocations over the years, and the Bogleheads community has tracked these revisions. The overall structure -- value tilt, international emphasis, REIT inclusion, short-term bonds -- has remained consistent across updates.
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Target Allocation
Performance Snapshot
Rolling Returns
| Period | Low | Average | High |
|---|---|---|---|
| 1 Year | -34.1% | +8.0% | +44.9% |
| 3 Year | -9.4% | +7.2% | +20.9% |
| 5 Year | -1.6% | +6.9% | +16.2% |
| 10 Year | +2.8% | +6.8% | +10.3% |
Growth of $10,000
Historical Drawdown
Percentage decline from the portfolio's peak value at each point in time.
Rolling Returns
Annualised return for each rolling period ending on that date.
Annualised return for each 1Y period ending on that date.