Looking at options trading activity among components of the S&P 500 index, there is noteworthy activity today in Illumina Inc (ILMN), where a total volume of 5,129 contracts has been traded thus far today, a contract volume which is representative of approximately 512,900 underlying shares (given that every 1 contract represents 100 underlying shares). That number works out to 70.9% of ILMN's average daily trading volume over the past month, of 723,035 shares..