Improving the Conventional Retirement Glidepath
December 10, 2013 - Strategic Allocation
Are there easily implementable life cycle investing strategies reliably superior to the conventional glidepath from equities toward bonds? In their June 2013 paper entitled “The Glidepath Illusion… and Potential Solutions”, flagged by a subscriber, Robert Arnott, Katrina Sherrerd and Lillian Wu summarize flaws in the conventional glidepath approach and explore simple alternatives that address some of the flaws. Specifically, they compare the follow six strategies:
- 80–>20: the conventional linear glidepath from 80% stocks-20% bonds to 20% stocks-80% bonds at retirement, with market capitalization weighting.
- 20–>80: inverse of the conventional linear glidepath.
- 50-50: constant 50% stocks-50% bonds, with market capitalization weighting.
- Dynamic Bond Duration: the 50-50 strategy, but: (a) hold 20-year bonds for the first 21 years; (b) shift linearly to 10-year bonds during the next ten years; and, (c) shift linearly from 10-year bonds to T-bills during the last 10 years before retirement.
- Dynamic Value/Low Beta: the 50-50 strategy, but: (a) stocks are weighted by book value for the first 21 years (from the 1,000 U.S. stocks with the highest book value); and, (b) shift linearly to low-volatility stocks (the 1,000 largest U.S. companies by market capitalization, weighted by inverse volatility) during the next 20 years.
- Dynamic Combined: the 50-50 strategy, but use Dynamic Bond Duration and Dynamic Value/Low Beta for bonds and stocks, respectively.
Comparison tests assume that: (1) each individual makes inflation-adjusted $1,000 annual contributions to a retirement portfolio over a 41-year career; and, (2) portfolio rebalancing is annual, frictionless and tax-free. Using simulations based on long-term samples of U.S. stock index, bond index and U.S. Treasury bill (T-bill) returns through the end of 2011, they find that: Keep Reading