Moderna will join the Nasdaq-100 index on October 9, replacing Warner Bros. Discovery, Nasdaq announced.
The change will alter the composition of one of the world’s most closely tracked technology-heavy equity benchmarks and can trigger portfolio adjustments by funds that replicate the index.
Index changes can generate automatic trading
The Nasdaq-100 tracks 100 of the largest non-financial companies listed on the Nasdaq Stock Market. When the membership changes, index funds and exchange-traded funds that follow the benchmark typically buy the incoming stock and sell the departing one to match the new weighting.
Moderna’s inclusion comes during a period of renewed investor interest in mRNA-based therapies and vaccines. The company has expanded beyond its original COVID-19 vaccine business into oncology and other infectious-disease programs.
Warner Bros. Discovery leaves amid corporate change
Warner Bros. Discovery’s removal reflects changes in index eligibility and corporate structure rather than a judgment about the company’s underlying business. Nasdaq periodically adjusts membership to keep the benchmark aligned with its methodology.
The effective date gives passive funds several trading sessions to prepare for the change.
Sources: Nasdaq announcement; Reuters, Oct. 2, 2026.
