As regulators signal a tighter focus on AI and machine learning, banks need to be vigilant about their internal models, as well as the models used by vendors, an expert says. As regulators zero in on how lenders are using artificial intelligence and machine learning in their operations, banks need to make sure they can adequately explain and monitor the models they use -- particularly if they are partnering with a vendor, said Joe Sergienko, managing director at Berkeley Research Group. "Does the bank understand what's going on inside the model, and can they articulate that in a reasonable enough way? That's a tough hill to climb in AI and machine learning models," Sergienko said. The Consumer Financial Protection Bureau (CFPB) issued a warning in May for lenders that use AI or machine learning to underwrite loans or issue credit, telling companies they need to be prepared to explain to customers the specific reasons for denying an application for credit.