Every corporation whose transactions are reported on the NYSE or AMEX ticker or on Nasdaq has been given a unique identification symbol of up to four letters. These symbols abbreviate the complete corporate name and facilitate trading and ticker reporting. Some of the most famous symbols are: T (American Telephone & Telegraph), XON (Exxon), GM (General Motors), IBM (International Business Machines), S (Sears Roebuck) and XRX (Xerox).