Is the conventional investment advice to allocate 60%-80% to stocks and 20%-40% to bonds in a personal long-term portfolio sensible? In his September 2026 paper entitled "Don't Fix Your Fixed Income Allocation", Douglas Lucas examines the historical U.S. experience of such advice based on Shiller's U.S. stock market and 10-year U.S. Treasury note (T-note) returns over investment horizons of 10, 20, 30 and 40 years. He adds 0.5% to T-note annual returns to account for the credit premium of corporate bonds. He rebalances annually. Using monthly Shiller data during January 1871 through June 2026, he finds that:
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