A Wall Street investor told Bloomberg TV Tuesday that Walmart is renting out space to banks that “exploit” the working poor.

The investor, Christopher Grisanti, co-founder of Grisanti Capital Management, said many of the independently-operated banks located in the retailer’s stores take advantage of cash-strapped consumers with nowhere else to turn. They allow poor Americans to overdraw their checking accounts and then subsequently charge overdraft fees.

“What’s happening in Walmart is you have these independently-owned branches that are exploiting a niche that’s been exploited for the last 100 years... the working poor, frankly, that can’t get credit elsewhere and can’t cash their checks,” he told Bloomberg TV’s Tom Keene.

Grisanti was discussing an investigation published Sunday in Wall Street Journal that the five banks with the most Walmart branches all crack the same top 10 list: banks that earn the most off overdraft fees in total. The five banks are Fort Sill National, First Convenience, Academy, Woodforest National and City National Bank and Trust Company.

A study released last June by the U.S. Consumer Financial Protection Bureau concluded that overdraft fees "have the capacity to inflict serious economic harm."

The study found that even though the Federal Reserve in 2010 made it so that banks could no longer automatically charge customers huge fees for overdrawing an account, banks' labyrinthine rules for overdraft protection leave customers vulnerable to increased costs and sudden account closures.

In an interview with The Huffington Post, Grisanti said the banks were taking a risk by relying on overdraft fees for a major chunk of their profits.

"It's a very risky business model, especially in an era where there's an anti-bank atmosphere for any bank," Grisanti told HuffPost, "especially for banks that appear to be exploiting the poor."

The investment manager told HuffPost that, despite being legal and regulated, the banks’ business model seems distasteful.

“I have no evidence of anything untoward,” said Grisanti. “It’s just a crummy way to make money.” Grisanti said his company would never include any such banks in its portfolio.

When contacted by HuffPost, Walmart spokeswoman Sarah McKinney appeared to agree with Grisanti. “We think banks charge too many fees,” McKinney said.

In October 2012, Walmart launched a prepaid card service called Bluebird in partnership with American Express, attempting to tap into the market of customers who don’t have checking accounts. Customers can’t spend money they haven’t loaded onto their Bluebird cards, so the service prevents them from overdrawing their accounts, while still providing the benefits of a debit card.

Still, surveyed customers say they want bank branches in the stores, and McKinney said leasing space to these banks provides shoppers with choice. She compared Walmart’s relationship with the banks to those with fast-food chains that lease space in its stores.