Looking at options trading activity among components of the S&P 500 index, there is noteworthy activity today in Mosaic Co (MOS), where a total volume of 22,343 contracts has been traded thus far today, a contract volume which is representative of approximately 2.2 million underlying shares (given that every 1 contract represents 100 underlying shares). That number works out to 48.8% of MOS's average daily trading volume over the past month, of 4.6 million shares..