Holding companies are conglomerates that own other firms. Investorwords offers a more specific definition: "A company that owns enough voting stock in another firm to control management and operations by influencing or electing its board of directors. Also called parent company."
A good example is Warren Buffett's Berkshire Hathaway
Another holding company is Loews Corp.
While many companies routinely gobble up other companies, they frequently aim to blend these acquisitions into their operations. Holding companies keep the businesses they buy more separate.
Longtime Fool contributor Selena Maranjian owns shares of Berkshire Hathaway.