Shares of Iamgold (NYSE:IAG) tumbled 6.11% in after-hours trading on Tuesday following the release of the company's first-quarter earnings report. The significant drop came as the gold miner reported mixed results, with revenue falling short of analysts' expectations despite a beat on earnings per share.

Iamgold announced quarterly revenue of $477.1 million, missing the FactSet consensus estimate of $500.9 million. This shortfall likely triggered the sharp sell-off in the stock. However, the company did report a positive surprise on the bottom line, with adjusted earnings per share coming in at $0.10, surpassing the analyst consensus estimate of $0.09 by 11.11%.

Despite the earnings beat, investors appeared to focus on the revenue miss. Compared to the same period last year, Iamgold's sales increased by 40.78%, rising from $338.90 million to $477.10 million. However, earnings per share declined by 9.09% year-over-year, dropping from $0.11 to $0.10. The mixed results, with strong sales growth but a slight earnings decline, suggest that the company may be facing cost pressures or operational challenges that are impacting its profitability.