Notable Monday Option Activity: TWTR, HP, PSA

Among the underlying components of the S&P 500 index, we saw noteworthy options trading volume today in Twitter Inc (TWTR), where a total of 135,813 contracts have traded so far, representing approximately 13.6 million underlying shares. That amounts to about 47.7% of TWTR's average daily trading volume over the past month of 28.5 million shares..