[Panos]

The comparison with Uber and Whatsapp is not the proper one. These are private companies that were funded and acquired, respectively, purely on growth potential.

OpenTable has been a public company for almost 5 years now (see http://finance.yahoo.com/echarts?s=OPEN). Revenues, cost, growth, and all other metrics have been publicly examined and scrutinized for long time. The 46% premium paid by Priceline is based on how the new management estimates that they can leverage the assets of Opentable and hardly a "bubble-ish" premium.

If you believe that OpenTable is part of a bubble, then the whole US stock market is in a bubble, which may be true but again not directly connected to Uber and Whatsapp valuations.