FORTUNE — Wal-Mart WMT is known for its low-cost products, but the independent banks that operate inside its stores aren’t following suit.

A report in the Wall Street Journal Monday says the five banks with the most Wal-Mart branches are among the top 10 U.S. banks in terms of charging fees, such as overdraft charges.

Most of the fees charged by the five banks operating in Wal-Mart stores come from overdraft charges, the paper said, while most U.S. banks earn the majority of their income through lending.

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Wal-Mart does not play a role in the operations of these banks, but a spokeswoman did tell the Journal that the megastore chain has a “very thorough process” for choosing which banks to lease space to.

Some of the top banks at Wal-Mart market their accounts to people who otherwise might not have access to banks, including those with bad credit histories, the Journal said.