AvantAir was recently taken public through a takeover by a publicly listed (shell) acquisition company - Ardent Acquisition Corp. This makes it the only pure play fractional aircraft company that is publicly traded.
The new company has retained the AvantAir name and trades under the stock symbol AACQ. The company is the exclusive North American provider of the Piaggio Avanti P180 aircraft, operating a fleet of 32 planes with another 51 Piaggio Avanti IIs on order.
You can also read about other fractional aircraft programs.