Thieves raiding his parents’ cash-and-carry once put a knife to Marria’s neck. He was just nine years old at the time. These days his software firm targets another type of criminal: fraudsters. Marria had been working as an executive director at the professional services firm EY before quitting to launch Quantexa. The London tech firm harnesses artificial intelligence to root out suspicious transactions from the IT systems of banks and other clients by knitting together and analysing data from a wide range of private and publicly available sources. The UK government hired Quantexa to identify fraudulent bounce-back loans secured during the pandemic. An investment round in April 2023 valued Marria’s London-based tech firm at around £1.5bn.