Lumentum Holdings shares surge 8.86% after-hours after promotion to S&P 500 index and new AI infrastructure partnerships.

Lumentum Holdings surged 8.86% in after-hours trading following its inclusion in the S&P 500 index, a promotion from the S&P MidCap 400 that highlights its rising market capitalization and strategic role in AI and cloud infrastructure. The move, effective March 23, 2026, typically attracts index-tracking fund inflows, boosting liquidity and investor interest. Concurrently, the company unveiled a VCSEL-based optical platform for AI data centers, emphasizing power efficiency and scalability, alongside expanded partnerships, including a multiyear, multibillion-dollar agreement with.