AirTree Ventures turned down a $400 million cheque for the fund it closed in 2016, and the fact it was offered betrays the Australian venture capital ecosystem's immaturity, according to AirTree partner Daniel Petre.

That fund, AirTree's second, ended up closing at $250 million and to raise any more would have been dangerous, Mr Petre told clients of Crestone Wealth Management at a panel in Sydney on Tuesday.