Mr. Bengen recently made a 2% investment in the stock of Archer Daniels Midland Co.

WSJ: Testing the 4%-a-Year Rule for Retirement Withdrawals

To provide a cushion for the portfolio, Mr. Bengen buys some funds that invest in dividend-paying stocks.

WSJ: Testing the 4%-a-Year Rule for Retirement Withdrawals

Bengen recently tested this formula against the decades of data that have accumulated since he first proposed the idea.

FORBES: "Do-it-Yourself" retirement income for business owners: the capitalization test - Part 1