Amarin (AMRN) is tumbling after the company said yesterday after the market closed that it would hire a U.S. sales force to sell its Vascepa fat reduction drug. The announcement indicates that Amarin doesn't currently plan to partner with another company on the drug or sell itself. Meanwhile, Amarin announced that it would raise $100M in non-equity financing. In a note to investors earlier today, research firm Leerink Swann wrote that it still believes that the company continues to look to sell itself. However, the lack of clarity on whether the company will receive five years of marketing exclusivity on Vascepa has made it difficult to price the asset, according to the firm, which maintained an Outperform rating on the stock. Separately Jefferies analyst Thomas Wei wrote in a note to investors earlier today that he had expected Amarin to hire a sales force, given the lack of clarity around Vascepa exclusivity. The analyst reported that the U.S. patent office had approved the company's ANCHOR 520 patent. The approval increases to 65% from 60% the probability that Vascepa will be granted exclusivity through 2030, Wei believes. The analyst maintained a $28 price target and Buy rating on the shares. In mid-morning trading, Amarin fell $2.24, or 18.74%, to $9.71.