Those watching the [Viekira Pak] launch through weekly prescription data from IMS Health were stymied by IMS' announcement that some of the prescriptions were not being reported due to "a contractual condition between a supplier and the manufacturer," and thus are being underreported, according to RBC Capital Markets analyst Michael Yee.
I recall similar scenario with certain Genentech’s drugs several years ago. It’s a dilemma for sell-side analysts, but it’s not a bad thing for buy-and-hold investors.