Looking at options trading activity among components of the S&P 500 index, there is noteworthy activity today in Microsoft Corporation (MSFT), where a total volume of 181,390 contracts has been traded thus far today, a contract volume which is representative of approximately 18.1 million underlying shares (given that every 1 contract represents 100 underlying shares). That number works out to 102.8% of MSFT's average daily trading volume over the past month, of 17.6 million shares..