Looking at options trading activity among components of the S&P 500 index, there is noteworthy activity today in T-Mobile US Inc (TMUS), where a total volume of 40,983 contracts has been traded thus far today, a contract volume which is representative of approximately 4.1 million underlying shares (given that every 1 contract represents 100 underlying shares). That number works out to 117.4% of TMUS's average daily trading volume over the past month, of 3.5 million shares..