Put Buying Picks Up During Regeneron Stock Rally

Regeneron Pharmaceuticals Inc (NASDAQ:REGN) has been rallying hard since its lows near $270 from early October, checking in 0.9% higher today at $375.40 -- which would be its best close since April -- after Credit Suisse this morning upgraded its rating to $400 from $340. This comes after REGN stock broke through the 320-day moving average last month, with the shares now sporting a three-month gain of 33.3%. During this surge, options traders have turned to long puts.

Specifically, the 10-day put/call volume ratio at the International Securities Exchange (ISE), Cboe Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX) checks in at 1.02 -- the first time long puts have outpaced long calls in this time frame since July. The current reading falls into the 92nd annual percentile, underscoring the strangeness of the trading action.

We should also point out that short interest keeps grinding higher on REGN, so sentiment is growing somewhat cautious outside the options pits, as well. In the last two reporting periods, short interest rose 11.3%, now at 2.36 million shares --  more than three times the average daily trading volume.