The reason is simple. In the next 1-2 years they won't be profitable. They will loose money!!! So is the calculation: in one year approx. still $ 200 Mio. cash from the IPO the company itself you can evaluate with only $ 150 Mio., because they loose money!!! in addition it is $ 350 Mio. - faire Value = $ 4,40 shareprice
This should be a faire value for the next 6 month.