William Bengen

William Bengen is a retired financial advisor widely known for his research on safe withdrawal rates for retirees. In 1994, Bengen published a landmark study titled "Determining Withdrawal Rates Using Historical Data" in the Journal of Financial Planning. This study investigated sustainable withdrawal rates from retirement portfolios invested in stocks and bonds, using historical market data.

Bengen's research concluded that a 4% initial withdrawal rate, adjusted for inflation annually, had a high probability of sustaining a portfolio for at least 30 years, based on historical U.S. market performance. This "4% rule" became a popular guideline for retirement planning and has been widely discussed and debated within the financial community.

His work has been influential in shaping retirement planning strategies and has prompted further research and analysis on optimal withdrawal rates, considering factors such as asset allocation, market volatility, and individual circumstances. Bengen has also written books and articles further elaborating on his findings and providing guidance on retirement income planning. He continues to be a respected figure in the field of retirement finance.