Nasdaq said the $70bn optical-technology company will replace CoStar Group, whose market value has fallen to about $13bn after its shares halved this year.
The move follows Lumentum's entry into the S&P 500 in March and comes after its stock rose 145% this year, following a 339% jump in 2025.
Investors have backed the company as AI-driven demand grows for its transceivers and lasers linking data centres. More than 200 investment vehicles tracking the index manage over $600bn.
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