MannKind is also the seventh-most shorted stock in the bio-pharma sector, with just under 29 percent of shares sold short as a percentage of the float. The MannKind short thesis is less about the risk of failed clinical trials and more focused on significant doubts about the company's ability to 1) get Afrezza approved; 2) find a marketing partner; and 3) generate meaningful revenue.
In the past two months, Vical's short interest has increased 32 percent and currently stands at 12.7 million shares.
GTx's short interest is relatively modest at just over 3 million shares. -- Reported by Adam Feuerstein in Boston. Follow Adam Feuerstein on Twitter.