Corning Inc. (GLW) shares tumbled 5.17% in pre-market trading on Tuesday, as investors grew increasingly cautious ahead of the company's second-quarter earnings report, which is expected before the market opens.

The decline comes amid mounting headwinds, with JPMorgan having placed the stock on its negative catalyst watch list due to elevated valuation levels and limited room for an earnings miss. Despite a roughly 40% pullback from its late-June highs, Corning still boasts a year-to-date gain of nearly 100%, keeping scrutiny on its valuation elevated. Market consensus estimates forecast adjusted EPS of $0.76 and revenue of $4.63 billion.

Broader weakness across the Electronic Components sector further amplified the downward pressure on Corning, with peers Coherent, Vishay Intertechnology, and Amphenol also trading lower in the pre-market session.