U.S. bank exposure to the Cayman Islands increased by $137.65 billion year over year to $510.85 billion as of March 31, making the island territory the U.S. banking industry's second-largest exposure after the U.K. at $540.40 billion.

Each of the "Big 4" U.S. banks reported at least a 30% increase in exposure to the Cayman Islands year over year. Bank of America Corp.'s exposure increased 70.9% to $59.58 billion while JPMorgan Chase & Co.'s exposure jumped by almost two-thirds to $144.65 billion as of March 31.

According to data from the Cayman Islands Monetary Authority, the number of licensed U.S. banks in the Cayman Islands has almost halved over the last five years, and U.S. banks now account for 16.5% of total banks in the country as of March 31, compared to 21.1% at the end of 2013.

In other foreign exposure changes, U.S. bank exposure to China fell by 6.0% over the last year to $107.87 billion, the largest percentage drop among nations where the U.S. has at least $100 billion of exposure.