Moderna Set to Replace Warner Bros. Discovery in Nasdaq-100 on October 9

Nasdaq announced that Moderna (MRNA) will become a component of the Nasdaq-100 Index before the market opens on Friday, October 9, 2026, replacing Warner Bros. Discovery (WBD). The index measures 100 of the largest non-financial companies listed on Nasdaq and is tracked by more than 200 investment products with over $800 billion in assets under management globally.

The vacancy comes from a deal, not a sector call. Paramount Skydance (PSKY) is acquiring Warner Bros. Discovery, and Reuters reported the merger is expected to close on October 6, with WBD also set to leave indexes run by MSCI and S&P. S&P Dow Jones Indices said Twilio (TWLO) will replace WBD in the S&P 500 before the open on Tuesday, October 6.

Moderna enters after an extraordinary run. Stocktwits reported the shares are up 541% year to date, driven by data showing its personalized cancer vaccine intismeran, combined with Merck's Keytruda, met its primary recurrence-free survival endpoint in August; Reuters put the company's valuation at roughly $75 billion. Investing.com reported the stock rose 2.2% in pre-open trading on October 2 to $193.15 and noted that index inclusion typically triggers mechanical buying. Citi analyst Geoff Meacham recently downgraded Moderna to Sell with an $80 price target, arguing a roughly 222% surge since mid-August outran what the pipeline can justify.

Dates to watch are the expected October 6 close of the Paramount Skydance deal and the October 9 effective date. Trading around those dates may show how much index demand is already priced in, while further intismeran data could matter more for the stock over time.