Shares of Amarin Corporation (NASDAQ:AMRN) lost nearly a fourth of their value today, plunging 24% on news that the FDA had officially rescinded its special protocol assessment, or SPA, for the phase 3 trial known as ANCHOR of the company's refined fish oil drug Vascepa, designed to lower triglyceride levels. The success of the trial, which did hit its primary and secondary endpoints before the FDA's decision to rescind the SPA, would have expanded Vascepa's potential market from fewer than 5 million patients to more than 30 million.

In this video, Motley Fool health-care analyst David Williamson looks at the company's next step with Vascepa after this decision, and other concerns, including a possible dilutive event for shareholders that some investors have speculated is on the horizon. David tells investors why he suspects that won't happen for quite a while yet but also notes that for investors thinking of buying today, positive catalysts may also still be a long way off, and it may be quite a while before Amarin is able to right its fortunes.