It’s not often that someone might regret making $31 million, the price paid by software giant Xero to buy fintech start-up Waddle last August. Last week, less than a year after that purchase, the Commonwealth Bank chose Waddle to power its return to invoice financing.

It is the kind of deal that can see a start-up soar, so did the Waddle founders - former schoolmates Leigh Dunsford, Nathan Andrews, and Simon Creighton - sell too early?