Looking at options trading activity among components of the Russell 3000 index, there is noteworthy activity today in Zillow Group Inc (Z), where a total volume of 18,031 contracts has been traded thus far today, a contract volume which is representative of approximately 1.8 million underlying shares (given that every 1 contract represents 100 underlying shares). That number works out to 41.6% of Z's average daily trading volume over the past month, of 4.3 million shares..