(Bloomberg) — American Express Co. and other credit-card issuers tumbled as JPMorgan Chase & Co. attributed weakness in its card business to rising costs on marketing and promotions, sparking concern over heightened competition.

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Shares of AmEx dropped as much as 4.5%, the most in more than a year, while Capital One Financial Corp. and Discover Financial Services each slipped at least 4%.

In a conference call with analysts, JPMorgan management said they expect marketing expenses to stay elevated as the bank seeks to expand market share. The comment came after the lender reported mixed third-quarter results.

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