Corning shares tumbled 5.09% in the 24-hour period ending early Wednesday, extending a sharp selloff that began after the optical networking company reported its second-quarter results. While the company delivered better-than-expected earnings and revenue for Q2, its forward guidance failed to meet elevated investor expectations, triggering widespread profit-taking.

The company posted adjusted earnings of 78 cents per share on core sales of $4.74 billion, both surpassing Wall Street estimates. However, its third-quarter core sales guidance of $4.9 billion to $5 billion was merely in line with the consensus of $5 billion, with the midpoint falling slightly short. This implied a sequential growth deceleration that spooked investors, especially given the stock's elevated valuation after a massive AI-driven rally.

Additionally, management cited capacity constraints and a smartphone slump as factors weighing on the outlook, despite strong demand for optical fiber from AI data centers. The selloff in Corning also dragged down the broader optical communications sector, with peers like Coherent and Lumentum recording double-digit losses.