"Private equity" refers to the entity in any privately owned business that is NOT traded on a stock market. Your neighborhood pizza establishment, if it is not part of a chain but is simply the result and destination for some local family's sweat, is a bearer of private equity. How much? That can at best be guesstimated, until such time as they try to sell it. The guesstimation would depend on similar businesses that have been sold recently in similar places. More specifically, "private equity" can refer to a private equity investment fund, like Mitt Romney's Bain Capital. This is a fund that focuses chiefly on operating businesses that are not exchange traded. A PE fund might buy the pizza place we have in mind. Ma and Pa might be thrilled by this, and take off to Florida for a well-earned and now well-financed retirement. Then Bain or a similar operation, might bring in new management, improve the profit margins, and then start shopping it around to the...