Lumentum Holdings, the photonics and optical technology company trading under the ticker LITE, is being added to the Nasdaq-100 Index effective May 18, 2026. It replaces CoStar Group (CSGP) in the index that tracks the 100 largest non-financial companies listed on the Nasdaq exchange.
The inclusion caps one of the more remarkable growth stories in the semiconductor-adjacent space. LITE shares have surged between 145% and 150% year-to-date in 2026, building on a 339% gain in 2025. The company’s market capitalization now sits at roughly $70 billion, dwarfing CoStar Group’s $13 billion valuation and making the swap look almost inevitable.
From niche optics to index heavyweight
The company specializes in photonic and optical technologies, the components that help data travel at the speed modern AI workloads demand. As hyperscale cloud providers have raced to build out the high-bandwidth networks needed to train and deploy large language models, Lumentum has found itself sitting on exactly the right product portfolio at exactly the right time.
Nasdaq announced the index change on May 8, 2026, and LITE shares ticked up 1.2% intraday on the news.
The road to the Nasdaq-100
This isn’t Lumentum’s first major index milestone in recent months. The company was added to the S&P 500 on March 23, 2026, a move that itself reflected just how quickly the company’s valuation and trading profile had expanded.
The Nasdaq-100 is a market-cap-weighted index, meaning larger companies carry more influence on its performance. At $70 billion, Lumentum won’t be one of the heaviest weights in the index, where Apple, Microsoft, and Nvidia command multi-trillion-dollar valuations.
CoStar Group, the commercial real estate data firm being removed, tells the other side of that story. At $13 billion in market cap, it no longer ranks among the 100 largest non-financial Nasdaq names.
What this means for investors
Index inclusion matters for reasons that go beyond prestige. When a stock joins the Nasdaq-100, every ETF and index fund tracking that benchmark has to buy shares. The Invesco QQQ Trust manages hundreds of billions in assets, and forced buying from passive vehicles creates structural demand for the stock.
For passive investors who hold broad market index funds, Lumentum’s inclusion means they now have exposure to the company whether they sought it out or not.