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Corning Incorporated (NYSE:GLW) delivered rapid optical growth on July 28, then suffered a share-price decline of more than 20% after its guidance fell short of elevated expectations. Coherent Corp. (NYSE:COHR) also traded sharply lower. Coherent belongs in this story for a specific reason: the two companies monetize different components of the same AI data-center links.

Corning Incorporated (NYSE:GLW) supplies the passive layer, including optical fiber, cable and dense connector systems. Coherent supplies active devices and modules, including lasers, photodiodes and 800G and 1.6T transceivers that convert electrical signals into light and back again. As clusters add accelerators, network builders need both more fiber paths and faster optical endpoints. Corning's order pace can therefore provide a partial read-through on the volume and timing of deployments that create transceiver demand for Coherent Corp. (NYSE:COHR). It cannot establish Coherent's market share, pricing or margins.

Corning reported second-quarter core sales of $4.74 billion, up 17% year over year, and core earnings of $0.78 a share, up 30%. Optical Communications sales increased 32% to $2.07 billion. Within that segment, Enterprise Networks grew 65%, and the company said generative-AI product sales grew significantly faster.

The disappointment came from the next quarter. Corning projected $4.9 billion to $5.0 billion of third-quarter core sales, about 16% year-over-year growth but slightly below Wall Street's expectation, according to Reuters. Optical growth also eased from 36% in the first quarter to 32% in the second. Corning had gained roughly 64% in 2026 through the prior close, leaving little room for even modest deceleration.

Coherent's own latest quarter, ended March 31, argues against treating Corning's guidance as proof of weaker Coherent operations. Revenue rose 21% to $1.81 billion, GAAP gross margin reached 37.7%, and management cited exceptionally strong data-center and communications demand while expanding capacity. Its product roadmap includes 1.6T transceivers, lasers and photodiodes for AI networks. Different customer mixes, active-component content and manufacturing yields can make its results diverge from Corning's.

Insider Monkey reported 91 hedge-fund portfolios with GLW long positions at March 31, 2026, up from 85 at December 31, 2025. That positioning preceded the earnings reaction and should not be read as a view on the new guidance.

The data showed 19,125,152 GLW shares sold short on July 15, equal to 2.23% of public float. Corning's latest 10-Q showed no convertible debt or pending stock merger. The low pre-event short float does not indicate a crowded bearish position and offers little basis for a squeeze thesis; it also does not explain the July 28 selloff.

While we acknowledge the potential of GLW and COHR as investments, we believe certain AI stocks offer greater upside potential and carry less downside risk. If you're looking for an extremely undervalued AI stock that also stands to benefit significantly from Trump-era tariffs and the onshoring trend, see our free report on the best short term stocks.

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