The 4% rule, which suggests that clients can safely withdraw 4% of their retirement savings each year and not run out of money, has been a guiding principle of retirement planning for a quarter century, helping millions of Americans determine how much they can safely withdraw from their portfolios.

But much has changed in recent decades. Longevity risk is a bigger concern for retirees, bond yields have plummeted, and new investments and digital assets are available to clients. 

Given…