Key Highlights

  • Amgen (NASDAQ:AMGN) rose 10.24% over one month to USD 453.65 in published market data as of October 28, 2026, and it is up 37.98% year to date and 19.46% over three months.
  • Second-quarter revenue reported on August 4, 2026 was about USD 10.1 billion, up 10%, with Repatha sales up 37% to USD 953 million as biosimilar competition cut Prolia and XGEVA sales by 33%.
  • Management raised its 2026 outlook, with the revenue midpoint moving to USD 38.8 billion from USD 37.8 billion and the adjusted EPS midpoint to USD 22.90 from USD 22.40.
  • No single October company announcement was found; the gain reflects a sector rally on October 20, 2026 and expectations for the MariTide obesity drug in Phase III.

Why There Is No Single Trigger

No Amgen press release dated October 2026 explains the move, so this is a momentum and sector story. On October 20, 2026 the S&P 500 Healthcare Index reportedly hit a new high and Amgen rose in morning trading alongside Pfizer, Johnson & Johnson and AbbVie. Commentator Jim Cramer described the shares on October 7 as a catch-up trade after a lag against the Dow. The stock closed at USD 434.03 on October 15, up 38.6% year to date at that point, and the 10.1% single-day drop on September 8 shows how quickly sentiment can change. Since the close before the August 4 release, the shares were up 15.2% by October 15, against 1.9% for the S&P 500.

The Fundamental Support

Six main growth drugs grew 26% in the quarter ended June and made up nearly 70% of product sales. Repatha, a cholesterol drug, grew 37% to USD 953 million, and on August 31 Amgen reported trial evidence that Repatha reduced the risk of death in high-risk adults without a prior heart attack or stroke. Prolia and XGEVA sales fell 33% as biosimilars launched, as management had expected. MariTide, an experimental obesity drug dosed monthly or less often, is in Phase III with nine studies running and three more planned, and it generates no revenue yet. Prolia and XGEVA erosion is a headwind that analysts watch each quarter, because it offsets growth in newer drugs.

Risks and What to Watch

Third-quarter results are expected on or around November 3, 2026, and management has warned that operating expenses will rise meaningfully, including a USD 100 million upfront payment for a business deal. MariTide must show tolerable side effects in late-stage trials, and Amgen halted its Phase I drug AMG 513 as the bar for obesity drugs is high. The shares trade at about 26.8 times trailing earnings against 22.7 times for the S&P 500, so execution matters. Investors should also remember that a 10.24% monthly gain and a 37.98% year-to-date gain raise the bar for the November report. Any slip in Repatha growth would also be noticed.

Where Things Stand

The answer is that Amgen (NASDAQ:AMGN) rose 10.24% because a healthcare sector rally, strong Repatha growth, a raised 2026 outlook and hopes for MariTide combined, not because of one October announcement. At USD 453.65 as of October 28, 2026, the shares trade near 26.8 times trailing earnings, so execution has to keep pace. The next catalysts are third-quarter results on or around November 3, 2026 and Phase III obesity data. A pause after such a run would not be unusual.