According to Fred Wilson, of Union Square Ventures, it's a movement. In fact, he argues that staying private and continuing to seek venture funding rounds, rather than going for a premature IPO, is the "new IPO." And he thinks this is good:
The IPO market for web companies we have right now is rationale. We can argue whether it is pricing these offerings correctly. But it feels about right to me. I believe we will see a bunch of IPOs next year, led by Facebook, which is the poster child of this whole "stay private longer" movement. If we as an industry can be patient, keep our companies private longer until they are truly IPO ready, then we should have a sustainable IPO market. That's where we seem to be headed. Let's not get greedy and screw it up.
I actually saw this in action (sort of) yesterday, when I did an AirTalk segment on reputation management with Michael Fertik, CEO of Reputation.com. His startup is on its forth venture round and has so far raised close to $70 million. I wondered why a company that's been around since 2006 is still in the VC space. But maybe the idea is to stay private until it truly makes sense to go public.
FYI, an "IPO" is an "initial public offering." It's the first time a previously private company sells stock to the public, to finance its ongoing operations and in the case of startups, pay off the early venture investors.
Bankrupt companies that were previously public can also launch IPOs, to return to the public markets. General Motors did this in 2010.