From "Exiting Your Business, Protecting Your Wealth" by John Leonetti:
Robert Avery of Cornell University has done extensive research into measuring the impact of retiring baby boomer business owners and what will happen from the illiquid wealth from those businesses. Avery states that "the majority of boomer wealth [in the United States today] is held in 12 million privately owned businesses, of which more than 70 percent are expected to change hands in the next 10 to 15 years."