Rambus Inc. (RMBS) experienced a significant 15.96% decline in its stock price during post-market trading on Monday. The semiconductor technology company's shares plummeted as investors reacted negatively to the company's forward-looking guidance.

While Rambus reported solid fourth-quarter 2025 financial results, with adjusted earnings per share of $0.68 meeting analyst expectations and revenue of $190.2 million beating estimates, the market focused on the company's outlook for the first quarter of 2026. The company projected product revenue between $84 million and $90 million for Q1 2026, which represents a potential sequential decline from the record $96.8 million achieved in Q4 2025 and falls below analyst forecasts of approximately $96.5 million.

The disappointing revenue guidance overshadowed the positive Q4 performance, which included 18% year-over-year revenue growth driven by DDR5 RCDs and record quarterly cash from operations of $99.8 million. The substantial after-hours selloff reflects investor concerns about the company's near-term growth prospects despite its recent strong quarterly results.