Still seems crazy high, but seemingly not out of line with other recent tech valuation multipliers. There are some other insights in these comments that seek to better explain the valuation.
[0] http://www.wired.com/2013/10/twitter-files-for-ipo-2/ [1] http://mashable.com/2014/04/16/weibo-ipo/
- a payment processor doesn't label all money flowing through the system as revenue, just their cut of it.
- a marketplace like Etsy has gross merchandise sales that tracks how much has been bought on their platform, and revenue just accounts for what they took in
An example: 1) An advertising agency buys media for a client to place ads in, but their contract with the media company says they will only pay for the media if they are paid by their client. In this case they can only recognize their commissions and fees as revenue, not the cost of the media itself. 2) An ad network buys media for a client but has to pay the media company for it whether or not the advertiser pays them. They can generally recognize the cost of the media as revenue, along with their commissions and fees.
AirBnb does not take risk on the portion of the customers' payments that go to the host: if AirBnb is not paid then the host is not paid, so this part of the payment is not recognized as revenue.