A symbol for an issuer's stock.
To get a quote for a company's stock enter the stock's symbol and the exchange suffix. For example, if you want an analysis for Vodafone, which trades on the London Stock Exchange, enter VOD.L in the ticker box on the main page, along with some other information about the options you hold, to get some idea of the value you receive from exercising a stock option today as opposed to waiting until later.
To use the calculator, you do not need to use an exchange suffix for securities traded on the major U.S. exchanges (NYSE, Nasdaq, and AMEX). However, quotes for OTC stocks and pink sheet stocks require the .OB and .PK suffix respectively.