Looking at options trading activity among components of the S&P 500 index, there is noteworthy activity today in Delta Air Lines Inc (DAL), where a total volume of 41,789 contracts has been traded thus far today, a contract volume which is representative of approximately 4.2 million underlying shares (given that every 1 contract represents 100 underlying shares). That number works out to 55.1% of DAL's average daily trading volume over the past month, of 7.6 million shares..