Lumentum joins NASDAQ-100 index, replacing CoStar Group on May 18
Lumentum Holdings, the company that makes the optical plumbing for AIs most power-hungry data centers, is getting a promotion. The photonics specialist will join the NASDAQ-100 Index on May 18, replacing CoStar Group, which was bumped due to its comparatively lower market capitalization. Nasdaq made the announcement on May 8, and the market responded predictably. Lumentum shares gained 5.39% in pre-market trading, a modest encore for a stock that has already climbed more than 1,200% since early 2024. The numbers behind the nod Look at Lumentums trajectory. The stock rallied 339% in 2025 alone, propelled almost entirely by demand for optical components that power high-speed data transmission in AI and cloud computing infrastructure. The companys most recent earnings report, from April 25, backed up the hype with actual revenue. Lumentum posted $452 million in Q1 2026 revenue, an 18% increase year-over-year. That growth came from the two sectors every hardware maker wants exposure to right now: artificial intelligence and cloud computing. CoStar Group, a commercial real estate analytics firm, drew the short straw in the NASDAQ-100‘s periodic rebalancing. The index regularly swaps constituents based on market capitalization, and CoStar’s valuation simply could not keep pace with the AI-fueled surge lifting companies like Lumentum. Why index inclusion