This industry comprises establishments primarily engaged in underwriting, originating, and/or maintaining markets for issues of securities, or acting as agents (i.e., brokers) between buyers and sellers in buying or selling securities on a commission or transaction fee basis. Investment bankers act as principals (i.e., investors who buy or sell on their own account) in firm commitment transactions or act as agents in best effort and standby commitments. This industry also includes establishments acting as principals in buying or selling securities generally on a spread basis, such as securities dealers or stock option dealers.