Notable Thursday Option Activity: C, MMM, UNH

Among the underlying components of the S&P 500 index, we saw noteworthy options trading volume today in Citigroup Inc (C), where a total of 58,524 contracts have traded so far, representing approximately 5.9 million underlying shares. That amounts to about 48% of C's average daily trading volume over the past month of 12.2 million shares..