I am very skeptical of short interest in a stock like AMRN. True, it could have gone from $3 to $1 or even a little lower on REDUCE-IT failure. On the other hand, it could have - and did - go over $20 on success. Just not a good stock to short, unless you have inside info, which the shorts in this case clearly did not.
I think that a lot of the shorting may have been by people who were using the proceeds of those shorts to buy call options.