Wells Fargo and BNP Paribas are among firms that will pay hundreds of millions of dollars in penalties for employees using unofficial communications like WhatsApp, personal texts or email to conduct business — the latest in US regulators’ crackdown on Wall Street’s failure to keep records. What began as a look at trading desks’ use of chat apps has expanded into a look into all of finance’s use of any kind of communication tool that doesn’t save records appropriately.