Theory developed by Harry Browne in the 1980s, the theory stated that a portfolio of assets equally split between growth stocks, precious metals, government bonds and treasury-bills would be an ideal mixture for investors seeking safety and growth.

The argument was that the portfolio would be profitable in all types of economic conditions: growth prosper in expansionary markets, precious metals in inflationary markets, bonds in recessions, and t-bills in depressions. In 1982 a portfolio was created with a mix similar to the theory stated and averaged an annual return of 6.38% over 25 years.