Interactive Brokers (NASDAQ: IBKR) saw its stock price plummet 5.14% on Thursday in after-hours trading, despite reporting better-than-expected third quarter earnings. The online brokerage firm posted adjusted earnings per share of $0.57, surpassing analyst estimates of $0.54.

The company's quarterly revenue also beat expectations, coming in at $1.66 billion compared to the $1.53 billion forecast. Key highlights from the earnings report include:

• Commission revenue increased 23% to $537 million on higher customer trading volumes
• Net interest income rose 21% to $967 million
• Customer accounts grew 32% year-over-year to 4.1 million
• Customer equity climbed 40% to $757.5 billion

Despite these strong results, investors appeared to focus on concerns about future growth and potential headwinds. During the earnings call, Interactive Brokers noted that while trading activity remained robust, there were signs of caution among investors regarding economic concerns. The company also faces challenges from a less favorable interest rate environment, with the Federal Reserve having cut rates for the first time since late last year.

The stock's sharp decline in after-hours trading suggests that market participants may be repricing their expectations for Interactive Brokers' future performance, even as the company continues to demonstrate solid growth in its core business metrics.