Long the darling of the credit-card industry, American Express Co. is looking awfully beaten-up lately.

The New York company's stock price is down 55% so far this year, including a 34% slide in October. The percentage of loans deemed uncollectible in a pool on which American Express reports monthly performance data reached 6.7% in September, up from 3.6% a year earlier. Earnings due after the closing bell Monday are expected to show a decline of more than 30% from last year's third quarter, according to Thomson Reuters.

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