Fintech start-up Afterpay has a neat product offering with the potential to turn the finance sector on its head, or at least severely disrupt it.

It lets people make immediate purchases online or instore and pay no money at the point of sale. Instead, they pay for the purchase in four instalments with no added fees or interest, except for late fees. For cash-poor millennials who are wary of credit card debt but want instant gratification, the service is a boon.

Retailers get more sales because their customers don't need to have cash to make a purchase. In exchange,