Domestic banks and U.S.-headquartered affiliates in Mexico have increased their supply of know-your-customer and transactional information to institutions in the United States under a bilateral agreement finalized last year, say sources. Until recently, Mexico's tough bank-secrecy and data-privacy rules almost entirely blocked financial services providers in the country from supplying anti-money laundering information across borders, impeding American and foreign lenders from meeting heightened legal and regulatory expectations back home. The informational logjam compelled some U.S. lenders to sever their correspondent ties to the country altogether. From 2010 through 2015, Mexican banks lost as many as 50 correspondent accounts at roughly...