I think the founders AirBnb and Uber are afraid to transition to being legit companies. The lack of IPO is just a part of it.

Not an answer to your question but semi-relatedly Scott Sumner had a post this week where he predicts that recessions will be significantly rarer in the future.

http://www.themoneyillusion.com/?p=32350

It's interesting to think about.

I would think that being well overdue for a recession and being in an objectively overvalued market would be a good reason to not want to get in now lest you be the one to IPO a week before judgement day. I heard on NPR today that one, if not the only, bull market to last longer than the current one ended with the dot com crash.

Because statistics are not laws of the universe? Because you may be misinterpreting the statistics? Because they're waiting their price to get higher in maybe 1 year, or maybe 7 years?

I would guess that its a combination of Sarbanes-Oxley and the glut of private capital available.

Maybe the smart money is on a market shock in the next several months and IPOs are leery of something terrible happening during the window between announcement and implementation. We do, after all, have a very strange political situation.