Rule No 1 Never Lose Money

This principle is one of Buffett's most repeated investing maxims. Its earliest documented appearance is in the October 27, 1986 issue of Forbes, where Buffett articulated it as a core rule of capital preservation. Benjamin Graham, Buffett's Columbia University mentor, had expressed a similar idea years earlier, and Buffett has consistently acknowledged that heritage. The rule is less a literal guarantee than a reminder that the mathematics of recovery are punishing: a 50% loss requires a 100% gain just to break even.