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Put Buyers Blast Red-Hot Genocea Biosciences Stock

Karee Venema

It's been a volatile stretch for Genocea Biosciences Inc (NASDAQ:GNCA) stock, per its 30-day historical volatility of 102.9%, a new 12-month high. Looking closer, the shares surged 25% on Friday thanks to news the company's lead cancer treatment, GEN-009, will be featured in the Journal of Clinical Oncology (JCO). And today, GNCA stock is up 54.2% at $8.68 -- fresh off an annual high of $11.28, and headed for its best day in three years -- on positive data for the vaccine.

Speculative players are rushing into GNCA's typically quiet options pits, too. At last check, 838 puts and 352 calls have changed hands -- almost 57 times what's typically traded in one day, and total options volume at a new 52-week peak.

The June 7.50 put has seen the most action so far, with nearly 530 contracts traded. It looks like new positions are being purchased here, meaning speculators are either betting on or initiating an options hedge against a quick retreat from the drug stock.

This growing skepticism toward GNCA is seen outside of the options pits. Short interest jumped 11.9% in the two most recent reporting periods to 1.43 million shares. This accounts for a healthy 11.4% of the stock's available float, or 21.9 times the average daily pace of trading -- and could be contributing to some of the equity's recent upside, as underwater shorts rush to cover.

gnca stock daily price chart on june 3