Questcor shareholders are left picking up the pieces after shares were nearly halved on Wednesday. The drop followed a clinical policy bulletin from insurer Aetna outlining a change in coverage policies for Questcor's flagship drug Acthar.

In an article written shortly after the news, Brenton said that shareholders had a right to be concerned about this issue, particularly the risk that more insurers would follow suit. After all, even though Aetna accounts for only around 5% of paid prescriptions of Acthar, its update largely excludes multiple sclerosis -- by far the most important indication for the drug -- from coverage going forward. If more insurers were to jump on the bandwagon, Acthar shipments could take a cliff dive.

However, Brenton feels slightly more comfortable after listening in on a call hosted by Questcor on Thursday morning. It's never bad to be skeptical of pronouncements from company managements, but in this case there were some valuable details on the dynamics at work with this drug, particularly in the MS indication.

In the following video, Brenton dives into some of that detail, as well as an interesting disclosure Questcor provides on its annual report that could have raised warning flags for investors.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.