Economics, business, accounting, and related fields often distinguish between quantities that are stocks and those that are flows.These differ in their units of measurement.A stock is measured at one specific time, and represents a quantity existing at that point in time (say, December 31, 2004), which may have accumulated in the past. A flow variable is measured over an interval of time. stockholder: One who owns shares of stock in a corporation or mutual fund. For corporations, along with the ownership comes a right to declared dividends and the right to vote on certain company matters, including the board of directors. also called shareholder.