The FFIEC data don’t include the exposure to China that banks have accumulated indirectly through their clients, said Mayra Rodriguez Valladares, managing principal at New York-based financial consultant MRV Associates LLC.

Banks “are lending to tons of different companies globally that are all sensitive to what’s happening in China,” she said. An Australian commodity producer with customers in China, for example, would give its bank additional, indirect exposure to China and yuan weakness.

The numbers “understate how badly a bank can be hit” by the Chinese slowdown, she added.

Ms. Rodriguez Valladares says the banks’ ability to cope with a slowing China has emerged in recent weeks as a frequent topic in her discussions with U.S. banking regulators.