Shares of Alpha & Omega Semiconductor (AOSL) tumbled 15.28% in after-hours trading on Wednesday following the company's fiscal first-quarter earnings report and disappointing revenue guidance for the second quarter.

The power semiconductor company reported its financial results for the fiscal first quarter ended September 30, 2025, after the market close. While the specific earnings figures were not provided in the available news, the market's sharp negative reaction suggests that the results or outlook may have fallen short of investor expectations.

The most significant factor driving the stock's plunge appears to be Alpha & Omega's revenue guidance for the second quarter. The company stated that it expects revenue for Q2 to be about $160 million, which likely falls below analysts' forecasts. This projection may indicate challenges in the company's near-term growth prospects or potential headwinds in the semiconductor industry.

Investors often react strongly to forward-looking statements and guidance, as these provide insights into a company's expected performance. The substantial after-hours decline in AOSL stock suggests that market participants are adjusting their expectations for the company's future financial performance based on this new information.