Looking at options trading activity among components of the S&P 500 index, there is noteworthy activity today in Penn National Gaming Inc (PENN), where a total volume of 20,924 contracts has been traded thus far today, a contract volume which is representative of approximately 2.1 million underlying shares (given that every 1 contract represents 100 underlying shares). That number works out to 47.5% of PENN's average daily trading volume over the past month, of 4.4 million shares..