Why optical stocks Lumentum and Coherent were the day’s biggest S&P 500 gainers

Optical component makers Lumentum and Coherent posted the strongest gains in the S&P 500, a move one expert tied to investors looking further down the AI data-center supply chain for demand signals. The shift in focus comes as questions linger about whether the pace of AI-related capital spending can hold.

The optical layer sits between chipmakers and the networking equipment that connects servers inside data centers. Companies in this segment supply the lasers, transceivers and photonic components that move data between compute clusters. For investors, their order books and guidance can serve as a read on whether AI infrastructure buildouts are broadening beyond the most visible names.

What to watch: upcoming earnings commentary on data-center demand, any changes in hyperscaler capital expenditure plans, and whether the gains hold or fade in the sessions ahead. Because optical suppliers sit deeper in the supply chain, their results may lag broader spending trends, making guidance and backlog disclosures particularly relevant for gauging the durability of the current cycle.