The AI infrastructure trade got a wake-up call on Tuesday, as a selloff in optical component stocks spread to ETFs that track a less flashy but critical part of the artificial intelligence boom: fiber optics and photonics.

Shares of glass and fiber optics giant Corning Inc (GLW) plunged 15% after the company reported better-than-expected second-quarter results but issued weaker revenue guidance for the current quarter. The stock was on track for its worst day since October 8, 2002, when it fell 17.3%.

Corning reported adjusted earnings per share of 78 cents, beating Wall Street expectations of 76 cents, while revenue came in at $4.74 billion versus estimates of $4.61 billion. However, the company forecast core revenue growth of 16%, or $4.9 billion to $5 billion, below FactSet's $5 billion estimate.

The weakness spilled across the optical supply chain, with shares of Lumentum Holdings Inc (LITE), Marvell Technology Inc (MRVL), AXT Inc (AXTI), and Coherent Corp (COHR) falling between 8% and 12% on Tuesday.

The selloff also hit optical-focused ETFs, with the KraneShares Photonic & Optical ETF (LUMA) down more than 10%, while the Tema Photonics & Optical ETF (LAZR) and Tuttle Capital Pure Play Photonics ETF (FOTO), the pure-play fiber and optics-focused ETFs, dropped between 9% and 11%.

AI's Next Bottleneck

While Nvidia Corp (NVDA) and other chipmakers have dominated the AI investment narrative, investors are increasingly focusing on the infrastructure needed to support increasingly complex AI workloads.

AI data centers require massive amounts of bandwidth to move data between GPUs, servers, and storage systems. Fiber optics, optical transceivers, lasers, and photonic technologies are becoming critical as companies look to improve speed, reduce latency, and lower power consumption.

Corning has emerged as one of the beneficiaries of this trend through its optical communications business. The company has signed multiple large-scale deals with hyperscalers, including a recent multi-year agreement to support Amazon.com Inc (AMZN)'s expanding data center network.

Tuesday's selloff, however, highlighted concerns that AI infrastructure suppliers may face tougher growth expectations despite long-term demand.

LUMA: A Direct Play on AI Optical Infrastructure

Among the hardest-hit ETFs was LUMA, which provides targeted exposure to companies involved in photonics and optical communications.

The fund includes companies across the optical supply chain, including:

• Lumentum Holdings, which develops optical and photonic products used in communications networks.
• Coherent Corp., a supplier of lasers and optical technologies.
• Marvell Technology, which provides networking chips used in AI data centers.
• AXT Inc., which supplies materials used in optoelectronics.

LUMA has become one of the closest ETF proxies for investors looking beyond AI chips toward the connectivity layer supporting the data center boom.

FOTO and LAZR Target the Broader Photonics Theme

FOTO focuses on companies where photonics is a core business, providing exposure to optical components, lasers, and communication technologies.

Meanwhile, LAZR takes a broader approach, investing across the photonics ecosystem, including optical communications, laser technology, sensing, and imaging companies.

Both ETFs have benefited from growing investor interest in the "AI beyond GPUs" theme, but Tuesday's declines showed their sensitivity to shifts in sentiment around AI infrastructure spending.

AI Optical Trade Faces a Key Test

The long-term case for optical infrastructure remains tied to the continued expansion of AI data centers. Hyperscalers are still investing billions of dollars into computing capacity, and the need for faster data movement is expected to increase as AI models become more demanding.

However, investors are becoming more selective about AI beneficiaries, particularly companies that have already seen significant valuation expansion.

For LUMA, FOTO, and LAZR, Tuesday's selloff represents a test of whether the optical layer of AI can maintain its momentum, or whether investors will demand clearer evidence that the fiber boom can translate into sustained earnings growth.