Week 46 Day 3: The Three-Fund Portfolio: The Bogleheads Classic

Bogleheads three-fund portfolio: 50% VTI (U.S. stocks), 20% VXUS (international stocks), 30% BND (bonds). Total expense ratio: approximately 0.05%. Covers approximately 15,000 stocks across 40+ countries plus 10,000 bonds. Annual maintenance: 30 minutes of rebalancing. This portfolio is more diversified than 99% of professionally managed funds and costs 95% less.

Three-fund allocation variations: Aggressive (young, long horizon): 60% VTI / 20% VXUS / 20% BND. Moderate (mid-career): 45% VTI / 15% VXUS / 40% BND. Conservative (near/in retirement): 30% VTI / 10% VXUS / 60% BND. Jack Bogle himself recommended: 0% international (he was skeptical of international diversification benefit for U.S. investors). The Bogleheads community generally recommends: 20-40% of equities in international (market weight is approximately 40%). Why three funds works: (1) Global diversification. VTI covers the U.S. market (approximately 60% of global stocks). VXUS covers the rest (Europe, Asia, emerging markets -- approximately 40%). Together: complete global equity coverage. (2) Protection against country-specific risk. What if the U.S. experiences a Japan-style lost decade? VXUS provides a hedge. (3) Bond ballast. BND provides stability, income, and rebalancing fuel. When stocks crash, bonds usually hold value (or gain), giving you cheap stocks to buy during rebalancing. Tax-efficient implementation: Taxable account: VTI (most tax-efficient) and VXUS (foreign tax credit usable in taxable accounts). IRA/401(k): BND (shield bond interest from tax). Roth IRA: VTI or VXUS (highest expected growth, tax-free forever). This three-account, three-fund structure is the optimal starting point for the vast majority of investors. Improvements beyond this point (adding SCHD, VTIP, SCHH, factor tilts) provide marginal benefit at increasing complexity.

The three-fund portfolio is approximately mean-variance efficient because it captures all three major investable asset classes (domestic equity, international equity, fixed income) in a low-cost, broadly diversified implementation. Empirical analysis (Bernstein, 2010; Swedroe and Berkin, 2015) shows that the three-fund portfolio captures approximately 95% of the risk-adjusted return available from more complex institutional portfolios (which add private equity, hedge funds, commodities, and real estate). The remaining 5% improvement from complexity is typically consumed by higher fees, illiquidity premia, and manager selection risk. The allocation between VTI and VXUS is the subject of ongoing debate. Market-cap weighting implies approximately 60% U.S. / 40% international (reflecting the relative sizes of U.S. and non-U.S. equity markets). Home-bias-adjusted allocation (accounting for the fact that U.S. investors' human capital and Social Security are already correlated with the U.S. economy) may justify a higher U.S. allocation (70-80% domestic). Vanguard's own research (2019) concluded that any allocation between 20% and 40% international provides most of the diversification benefit. The bond allocation is typically chosen based on risk tolerance and proximity to retirement, following the heuristic 'bond percentage = age' (a 35-year-old holds 35% bonds) or more nuanced approaches based on required withdrawal rate and sequence risk. The three-fund portfolio's enduring appeal lies in its combination of theoretical soundness, practical simplicity, extreme low cost, and behavioral robustness -- it is the 'good enough' portfolio that very few investors have the discipline to hold throughout a full market cycle.