KLA-Tencor's stock experienced a significant after-hours plunge of 5.03% following the release of its fiscal second-quarter financial results. The semiconductor equipment maker reported its earnings after the market close, triggering a sharp sell-off in extended trading.

The company reported Q2 adjusted earnings of $8.85 per share, beating analyst estimates of $8.79, while revenue of $3.30 billion also exceeded expectations of $3.25 billion. For the third quarter, KLA provided guidance for adjusted EPS of $9.08 (plus or minus $0.78) on revenue of $3.35 billion (plus or minus $150 million), which at the midpoint exceeds analyst forecasts of $8.97 EPS on $3.29 billion revenue.

Despite the earnings beat and guidance that appears strong at first glance, investors reacted negatively to the report, sending shares lower in after-hours trading. The market's response suggests concerns about the company's outlook or specific elements within the financial results that outweighed the positive headline numbers.