Together, they account for five of the nine banks the state fund says it uses for foreign exchange. As more and more banks enter guilty pleas, it makes it increasingly tough for clients to cut them out on principle.

The Texas pension fund resumed business with Credit Suisse “after due diligence was performed and concluded to satisfaction,” Mary Jane Wardlow, a fund spokesman, said in an email.

The fund has procedures to “mitigate exposure to those types of improper dealings in the market” among the firms it uses for trading currencies, Wardlow said. Those practices include keeping dealers from knowing whether they're buying or selling a security until they execute the trade, she said.

Waivers Granted

Six of the world's largest banks agreed to pay $5.8 billion May 20, and five pleaded guilty to charges tied to market-rigging probes. They include Citigroup, JPMorgan, Barclays, Royal Bank of Scotland for colluding in currency markets, and UBS's main banking unit in interest-rate manipulation.

The U.S. Securities and Exchange Commission granted waivers last week that allow the five banks to continue doing business unimpeded, according to a person with direct knowledge of the decision.

“We're taking the sting out of what it means for a firm to be convicted of a crime,” said Bartlett Naylor, financial policy advocate with Public Citizen, a Washington nonprofit. “The choice of banks is limited on Wall Street because crime has become so pervasive.”

–With assistance from Dave Michaels in Washington.

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