RE:RE:RE:GUD valuationMcGill surveyed potential buyers of the PRV: https://www.plosntds.org/article/info%3Adoi%2F10.1371%2Fjournal.pntd.0001750
One company stated they would pay over $400mm. Another said they would pay between $200mm and $300mm. Only 5 were surveyed.
Or you can come up with your own valuation. it's a simple DCF, as the PRV allows cash flows to be moved forward. This gets you to $300mm: https://www.imshealth.com/imshealth/Global/Content/Document/Placing_Value_on_FDA_Priorities.pdf
It's fairly simple. Saying its worth zero or only $4mm is just ignorant, and if you sold the stock based on that, you didn't do sufficient research. Obviously there's risk here, and nothing's guaranteed. Only 2 PVRs have ever been issued, and none have ever sold (or been for sale).