What happened

Shares of Amarin (AMRN -2.92%), a company marketing a purified fish-oil pill, popped after the company's J.P. Morgan Healthcare conference presentation. The stock rose 13.6% in midday trading, and was up 9.3% as of 3:53 p.m. EST on Thursday.

Check out the latest Amarin earnings call transcript.

So what

Amarin has been one of 2018's best-performing stocks because its lead drug, Vascepa, produced stunning cardiovascular-event outcome data last September. During the Reduce-It study, patients who added Vascepa to their regular statin therapy were 25% less likely to suffer a heart attack or other major cardiovascular events.

Businessman drawing an upward-sloping chart with his finger

Image source: Getty Images.

The stock gave up some gains in late 2018, due to concerns that the mineral-oil capsules investigators used as a placebo may have elevated cholesterol levels in the control group. During today's investor presentation, Amarin soothed concerns.

Now what

As the only fish-oil capsule of its kind, Amarin can make it rain for investors if the Food and Drug Administration expands its label to include patients who can't control their cholesterol on statin therapy alone. Vascepa is currently approved to treat around 3.8 million Americans with high triglycerides, as an adjunct to diet.

In the first quarter, the company will submit an application that could expand Vascepa's sales many times over, by including cardiac-event reductions for the enormous population of patients on statin therapy with high triglyceride levels.

Fourth-quarter revenue rose to between $72 million and $76 million, which at the low end is a 31% increase compared to the third quarter. In 2019, Amarin expects total revenue to rise more than 50% to around $350 million.