Shares of Total System Services Inc. fell Friday after a stock downgrade prompted by the Columbus Ga., company's exposure to the Washington Mutual Inc. failure.

The sale of Washington Mutual's assets to JPMorgan Chase & Co. "will likely represent a meaningful loss of business, as JPM is a licensing partner of TSYS and does not use them for actual processing," Craig Maurer, an analyst at Credit Agricole Group's Calyon Securities, wrote in a research note issued Friday.

Mr. Maurer downgraded TSYS' stock to "neutral," from "buy."

When banking companies are acquired, "there is a significant chance that the processing business will change hands, and even if the acquiring bank is a TSYS customer, it is likely that the contract terms around the acquired business will be renegotiated," he wrote.

In addition, consumers are shifting their spending habits to debit cards, Mr. Maurer wrote; transaction growth for debit cards is outpacing spending on credit cards by 3 to 1 in recent months, and TSYS "does not have a material debit processing business."

By Friday afternoon, TSYS' shares had declined 6.34% from Thursday's close, to $17.14.