Shares of ACM Research Inc. (ACMR) tumbled 9.51% in pre-market trading on Wednesday, despite the company reporting better-than-expected third-quarter revenue. The sharp decline comes as investors appear concerned about margin compression and potentially slower growth ahead.

ACM Research, a supplier of wafer processing solutions to semiconductor manufacturers, announced Q3 revenue of $269.16 million, surpassing the IBES estimate of $251.7 million. The company reported earnings per share of $0.52 for the quarter. However, gross margin declined significantly to 42% from 51.4% in the same period last year, indicating increased cost pressures.

While ACM Research's top-line growth impressed, the margin contraction seems to have spooked investors. The company's operating income came in at $28.923 million, with net income reaching $35.889 million. Looking ahead, ACM Research narrowed its full-year 2025 revenue guidance to a range of $875 million to $925 million, which may suggest a more conservative outlook for the fourth quarter.