BacktestFolio · Glossary
Trinity Study
In plain language
Over 30 years, in many of the historical periods they analysed, a 4% initial withdrawal adjusted for inflation held up for equity-heavy portfolios. On their sample it reads as a historical frequency.
Technical definition
1998 study by Cooley, Hubbard and Walz (Trinity University) on withdrawal rates from retirement portfolios using historical US market data. It popularised portfolio success rates and reinforced use of the '4% rule' already proposed by Bengen in 1994.