In a stylish open-plan office in Sydney’s CBD, around 30 artificial intelligence technology engineers are building cutting-edge software to help banks retain their mortgage customers.

This specialist team – working for start-up Elula – is considering one of the biggest operational risks banks will face in 2023. That is: how to prevent more than $200 billion in home loans, written on ultra-low interest rates during the pandemic, being switched to other banks when the fixed terms expire.