Treasury stock is stock issued by the U.S. Treasury Department. corporate stock issued by the treasurer of a company. a corporation's own stock, which has been reacquired and held for future use. stock purchased by a corporation and held as an investment in its treasury. Treasury stock is stock issued by the U.S. Treasury Department. corporate stock issued by the treasurer of a company. a corporation's own stock, which has been reacquired and held for future use. stock purchased by a corporation and held as an investment in its treasury