You are looking at a chain in which there are standard and non-standard options. For a detailed understanding of non-standard options you might want to review the following: http://derivativedigest.com/Videopedia/nonstandard.html There you will find a basic explanation of non-standard options. These often happen if there is a special dividend awarded, certain M&A activities, certain stock dividends, et al.. after a chain is initially created. This is not free money! There is a non-standard/adjusted option. You can find the specific provision inherent to this option and determine if there is a potential (very unlikely) arbitrage opportunity, but be very wary. This is not at all likely to occur.