Looking at options trading activity among components of the S&P 500 index, there is noteworthy activity today in Costco Wholesale Corp (COST), where a total volume of 12,230 contracts has been traded thus far today, a contract volume which is representative of approximately 1.2 million underlying shares (given that every 1 contract represents 100 underlying shares). That number works out to 51.4% of COST's average daily trading volume over the past month, of 2.4 million shares..