The owners value shares at less than the proportional value of underlying assets on the theory that fractional interests in a portfolio are not worth as much to outsiders.

FORBES: Family Inc.

Today modern portfolio theory is used to justify the inclusion of even the riskiest assets in significant percentages.

FORBES: The Shape of Things to Come (December 1, 2001)

Translated into investment theory, this means investors should aim to hold a portfolio of assets whose returns are not highly correlated.

ECONOMIST: Unscrambling correlation