The numbers speak for themselves. So far this year, just 70 companies have sold shares to the public for the first time. That's half the pace of last year and a fraction of the 213 IPOs over the same period in 2014. Why are companies staying private longer, or selling themselves, instead of going public? Does 2017 herald a revival of the IPO market, or should we expect more of the same? Bloomberg IPO reporter Alex Barinka explains to host Alex Sherman why companies decide to go public and what's on tap for next year.