A Simple Diversified Portfolio Framework for Ages 70-79

What Does a Simple Portfolio Look Like at

A simple diversified portfolio at Ages 70-79 has two or three components: a total US stock market index fund (or S&P 500 index fund), a total international stock market index fund, and a total bond market index fund (for investors who need a bond allocation). 40-55% equity is appropriate for most 70s investors who still have 15-25 years of potential longevity to plan for. Eliminating equities entirely is a longevity risk. The US/international split within the equity allocation is typically 60-70% US, 30-40% international, mirroring the global market-capitalization split. Target-date funds apply this split automatically.

Intermediate-term bond funds and high-quality short-term bonds provide income and stability. TIPS (Treasury Inflation-Protected Securities) can help preserve purchasing power over a long retirement. The most important variable in the portfolio is the total equity-to-bond ratio. Research on long-term returns consistently shows that allocation is the primary driver of outcomes, not fund selection within each category. Choosing between two low-cost total market index funds is far less consequential than choosing the right equity-to-bond ratio.

When Should You Rebalance?

Rebalance when any asset class drifts more than 5 percentage points from its target. If your target equity allocation is 80% and the portfolio reaches 85% or 75%, that is the rebalancing trigger. Time-based rebalancing (quarterly or annual regardless of drift) produces similar outcomes to threshold-based rebalancing but requires more transactions. The 5% threshold rule typically triggers rebalancing once every 1-3 years in normal markets, which is appropriate for a casual investor with other demands on time.

The tax implications of rebalancing depend on account type. In tax-advantaged accounts (401(k), IRA), selling overweight assets and buying underweight assets has no immediate tax consequence. In taxable brokerage accounts, selling a gain-generating asset triggers a capital gains tax. In taxable accounts, consider rebalancing primarily by directing new contributions to underweight asset classes rather than selling overweight ones.

What Expense Ratios Are Acceptable for This Portfolio?

Expense ratios below 0.10% are excellent and available from Vanguard, Fidelity, and Schwab for their total market index funds. Expense ratios between 0.10% and 0.20% are acceptable. Expense ratios above 0.50% are a meaningful performance drag over long periods and should be replaced with lower-cost equivalents when available. The difference between a 0.05% expense ratio and a 0.50% expense ratio on a 100,000 dollar portfolio over 30 years, assuming 7% annual growth, is approximately 120,000 dollars in additional wealth from the lower-cost fund. Fund expenses are a guaranteed cost subtracted from returns every year regardless of market performance.

Frequently Asked Questions