American Express shares tumbled 6.05% in pre-market trading on Friday after the credit-card giant reported second-quarter results that beat profit expectations but showed a slight revenue miss and maintained earnings guidance, disappointing investors who had hoped for stronger growth signals.

The company posted diluted earnings per share of $4.53, handily surpassing the consensus estimate of $4.40, while net income rose 8% to $3.11 billion. However, total revenue net of interest expense came in at $19.64 billion, just below the $19.69 billion to $19.71 billion analysts had forecast. Card member spending, or billed business, climbed 9% on a foreign-exchange adjusted basis, the fastest growth in three years, but failed to show the acceleration some investors were seeking.

While American Express raised its full-year revenue growth guidance to 10% from a prior 9%-to-10% range, it only reaffirmed its earnings per share outlook of $17.30 to $17.90. Analysts noted that the market was disappointed by the lack of acceleration in both billed business and revenue growth, and had hoped for a more bullish forecast. The company’s plans to reinvest its recent outperformance back into the business also weighed on sentiment, as the maintained profit guidance suggested limited near-term upside.