Amgen (AMGN) Shares Decline 5% Following Novartis Drug Trial Failure

Amgen Inc. (NASDAQ: AMGN) lost approximately $12 billion in market value after its stock fell about 5% to $415 on September 4, 2026. This decline was triggered by Novartis's announcement that its Lp(a)-lowering drug, pelacarsen, failed in a Phase 3 trial, jeopardizing the validity of similar drugs, including Amgen's olpasiran. Despite the drop, Amgen has other products driving value, such as MariTide, Repatha, and Tezspire, which provide some stock resilience. This is significant for investors considering the impact of trial results on biotech stock valuations and the importance of diversification in Amgen's portfolio.