Corning Inc. (Corning (GLW)), the specialty glass supplier best known for making the screens on iPhones and Apple Watches, had a rough Tuesday despite delivering a second-quarter earnings report that most companies would kill for. The stock dropped about 20% after the company's third-quarter revenue guidance came in roughly in line with Wall Street expectations — a classic case of "good news isn't good enough" when a stock has already more than doubled over the past year on AI hype.

Let's start with the numbers, because they really were impressive. Adjusted earnings rose 30% year over year to 78 cents per share, beating the 76 cents analysts were looking for. Revenue climbed 17% to $4.74 billion, ahead of the $4.61 billion consensus. Core gross margin expanded 120 basis points to 39.6%, and core operating margin improved 190 basis points to 20.9%. The company generated $1.72 billion in GAAP operating cash flow and $1.42 billion in adjusted free cash flow during the quarter. That's a lot of green ink.

The star of the show was Optical Communications, where revenue jumped 32% to $2.07 billion. That was fueled by a 65% surge in Enterprise Networks, with GenAI-related products growing even faster. Solar revenue also had a moment, soaring 90% to $438 million, though Corning noted profitability there should improve in the third quarter after some facility upgrades. Glass Innovations, the segment that includes the iPhone glass, eked out just 1% growth to $1.46 billion, while Automotive sales rose 2% to $471 million. So the AI tailwind is real, but it's not lifting every boat equally.

Corning has been busy signing deals to capitalize on the AI infrastructure boom. During the quarter, it inked a multiyear agreement with Amazon.com Inc. (Amazon (AMZN)) to supply optical fiber, cable, and connectivity solutions for U.S. data center expansion. It also expanded its partnership with NVIDIA Corporation (NVIDIA (NVDA)), with plans to increase U.S. optical connectivity manufacturing capacity tenfold and boost fiber production capacity by more than 50% to support growing AI infrastructure demand. These are the kinds of headlines that sent the stock soaring over the past year.

But here's where the story gets tricky. For the third quarter, Corning expects adjusted earnings of 85 to 89 cents per share, compared with the analyst estimate of 85 cents — so basically in line. Revenue is forecast at $4.9 billion to $5.0 billion, representing about 16% year-over-year growth and right around the $4.97 billion consensus. That's solid, but after a year where the stock doubled on AI optimism, investors were hoping for something that would justify even higher valuations. Instead, they got a "meets expectations" guidance, and the market decided to take some profits.

Management did offer some longer-term carrots. They projected a 19% sales compound annual growth rate from the fourth quarter of 2026 through the fourth quarter of 2030. They also said they're making progress under their upgraded Springboard Plan, targeting annualized sales of $20 billion by the end of 2026, $30 billion by 2028, and $40 billion by 2030. The Solar business is expected to become a larger earnings contributor starting in the third quarter, targeting more than $3 billion in annual revenue with strong profitability. So the story isn't broken — it's just that the market's expectations had gotten ahead of reality.

The selloff wasn't limited to Corning. Other optical networking and photonics stocks also caught a cold, with shares of Ciena Corp. (Ciena (CIEN)), Coherent Corp. (Coherent (COHR)), and Lumentum Holdings Inc. (Lumentum (LITE)) all moving lower in sympathy. When the leader in a hot sector stumbles — even if it's more of a stumble in perception than in actual results — the whole group tends to feel the pain.

So what's the takeaway? Corning is executing well in a massive growth market. The AI infrastructure buildout is real, and Corning's optical products are essential for the high-speed data centers that power it. But the stock's 100%+ run over the past year meant that any quarter that didn't blow the doors off was going to be punished. Sometimes the market's expectations are the toughest competitor of all.