Week 46 Day 1: The One-Fund Portfolio: Total Simplicity

Vanguard Target Retirement 2055 (VFFVX): 90% stocks (U.S. and international), 10% bonds. Expense ratio: 0.08%. As you approach 2055, it automatically shifts to more bonds. By 2055, it will be approximately 50/50 stocks/bonds. After 2055, it continues shifting to approximately 30/70. You never touch it. You never rebalance. You never make a decision. Total cost of being wrong: $0.

The case for the one-fund portfolio: (1) Behavioral perfection. With one fund, there is nothing to tinker with. No switching from VTI to SCHD chasing performance. No abandoning international when U.S. outperforms. No panic-selling bonds during a rate hike. The single biggest drag on investor returns is behavioral errors -- the one-fund portfolio eliminates nearly all of them. (2) Automatic rebalancing. The target-date fund rebalances internally. When stocks surge, it sells some stocks and buys bonds. When stocks crash, it sells bonds and buys stocks (buying low automatically). You get systematic rebalancing without effort. (3) Cost efficiency. Expense ratios of 0.08-0.15%. Only slightly higher than holding the underlying funds individually (0.03-0.05%). The convenience premium is 0.03-0.10% -- trivial for the certainty it provides. (4) Professional glide path. The allocation shift from stocks to bonds follows a research-backed glide path. You do not need to decide when to reduce stocks. Limitations: (a) No tax optimization. Target-date funds in taxable accounts distribute capital gains and dividends that you cannot control. Best used in tax-advantaged accounts (401k, IRA). (b) No asset location. You cannot put bonds in IRA and stocks in taxable if you hold a single target-date fund. (c) Slightly higher expense ratio than DIY. (d) No customization for personal risk tolerance (the glide path is one-size-fits-all). Who should use this: (a) Anyone who does not want to manage their portfolio. (b) 401(k) investors with limited fund choices. (c) New investors who are overwhelmed by options. (d) Anyone who has historically made behavioral mistakes with a more complex portfolio.

Target-date funds (TDFs) have become the dominant default investment in U.S. employer-sponsored retirement plans following the Pension Protection Act of 2006, which designated them as Qualified Default Investment Alternatives (QDIAs). As of 2023, approximately 60% of 401(k) assets from new contributions flow into TDFs. The academic evidence supports TDF effectiveness: Mitchell and Utkus (2020) found that 401(k) participants in TDFs exhibited significantly fewer behavioral errors (panic selling, performance chasing, neglect of rebalancing) than self-directed participants. Morningstar's annual 'Mind the Gap' study consistently shows that TDF investors capture a higher percentage of their funds' total return than self-directed investors -- precisely because the single-fund structure eliminates the most common behavioral mistakes. The glide path design (the schedule of equity/bond allocation changes over time) varies across fund families. 'To' glide paths (Vanguard, Fidelity) reach their most conservative allocation AT the target date and then remain static. 'Through' glide paths (T. Rowe Price) continue shifting to more bonds for 10-30 years AFTER the target date. The 'through' approach aligns better with the bond tent research (maintaining higher equity allocation beyond the retirement date) but creates more risk at the retirement transition. For most investors, the TDF approach is not theoretically optimal but is behaviorally optimal -- the gap between the theoretically perfect portfolio and the TDF is approximately 0.1-0.3% per year, while the gap between the average self-directed investor and the TDF is approximately 1-2% per year due to behavioral errors.