Retirement withdrawal backtest

Each start month from January 1871 is run separately, using only what U.S. stocks, bonds and prices actually did in the months after it. The withdrawal comes out at the start of each month, a twelfth of the year's amount, and the fee comes out at the end of each month. Stocks and bonds are put back to the chosen mix once a year.

Stocks are the S&P Composite with dividends reinvested. Bonds are approximate: a 10-year Treasury bought at each month's yield and sold a month later. Prices are monthly averages of daily closes.

Balances are after inflation, in each start month's dollars, and before any tax. The money has run out when a month's withdrawal can't be paid in full.

Start months overlap: a 30-year period starting in May 1965 shares 29 years and 11 months with one starting in June 1965. So the share of start months that lasted is not a count of separate outcomes.