The year 2006 is almost pre-history in terms of modern technology. That was when Amazon Web Services was launched, and a year before the birth of the iPhone. Facebook had been founded only two years previously.

It is also when streaming music service Spotify appeared on the scene. A year later brought Dropbox, which is used to store and sync information between devices. Smartphones breathed life into these services, and a private market awash with cash inflated their valuations.

The time has finally come for a reckoning. The “deca-unicorns” — private tech companies worth more than $10bn — are finding their way to Wall Street. But while they have often led a charmed life in private, the public markets look like they will be less accommodating.