OHR Pharmaceutical Inc (OHRP), ImmunoGen, Inc. (IMGN) Among Biotech Leaders

U.S. stocks are comfortably higher this afternoon, taking cues from their European and Chinese peers. More than 1,800 Nasdaq-listed stocks are higher at last check, compared to just over 700 losers. Healthcare stocks are among the leaders -- the iShares Nasdaq Biotechnology ETF (IBB) is 1.5% higher at $378.30 -- including OHR Pharmaceutical Inc (NASDAQ:OHRP), ImmunoGen, Inc. (NASDAQ:IMGN), BioLife Solutions Inc (NASDAQ:BLFS), and Celsus Therapeutics PLC (ADR) (NASDAQ:CLTX), which are following in the footsteps of Anacor Pharmaceuticals Inc (NASDAQ:ANAC). 

OHRP is more than 50% higher at $3.41, thanks to positive data on squalamine, the company's eye drop. The shares are on pace to end the week atop their 10-week trendline for the first time since late March, but have seemingly run into a speed bump in the form of their 20-week moving average.   

Against this backdrop, OHRP calls are flying off the shelves at 79 times the average intraday pace, and have outnumbered puts by a margin of more than 4-to-1. Specifically, traders are buying to open October 2.50 calls, on expectations for OHRP to extend its journey north of $2.50 through October options expiration. 

The preference for bullish bets represents a shift in sentiment for OHR Pharmaceutical Inc. The stock's Schaeffer's put/call open interest ratio (SOIR) of 0.62 stands higher than 82% of all other readings from the past year, suggesting near-term option traders are more put-biased than usual right now. 

IMGN has skyrocketed 14.7% to sit at $16.54, and earlier notched an annual high of $16.63, despite the lack of a clear driver. The stock's 30-day at-the-money implied volatility has soared 16.1% to 68.6% -- in the 79th percentile of its annual range -- and calls are running at twice the average afternoon clip, with bullish buy-to-open action spotted at the July 16 call. 

As with OHRP, today's affinity for long calls marks a change of pace for IMGN. On the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), the stock's 50-day put/call volume ratio of 0.36 stands higher than 77% of all other readings from the past 12 months. Likewise, the equity's SOIR of 0.95 registers in the 89th percentile of its annual range. 

A short squeeze could add fuel to ImmunoGen, Inc.'s fire, though. Short interest accounts for 13.7% of the stock's total available float, representing nearly eight sessions' worth of pent-up buying demand, at the equity's average pace of trading. 

BLFS has advanced 6% to wink at $2.12, after the company offered upbeat second-quarter product revenue. The stock is on pace to topple its 20-day moving average for the first time since mid-June. The recent crop of shorts could be running scared now, as short interest more than tripled during the past two reporting periods.

CLTX was briefly halted ahead of the bell, but was last seen 21.2% higher at $0.59, after the firm agreed to buy privately held Volution Immuno Pharmaceuticals SA in an all-stock transaction. For more stocks making moves on Merger Monday, click here.