AstraZeneca vs. Merck: Which Pharma Giant Holds the Key to Growth

AstraZeneca and Merck are two leading pharmaceutical companies with diverse portfolios. While both have significant growth potential, their strategies and pipelines differ.

Merck's oncology segment accounts for over 60% of its pharma sales, led by the blockbuster drug Keytruda. The company expects Keytruda to achieve peak sales of $35 billion by 2028. Merck also has a strong presence in vaccines, neuroscience, and animal health.

AstraZeneca's oncology segment represents about 46% of its total revenues, with segment sales rising 15% at constant exchange rates in the first half of 2026. The company has a broad portfolio across immunology, rare diseases, vaccines, and cardiovascular/respiratory medicine.

Both companies have solid revenue and earnings growth and promising long-term pipelines. However, Merck's excessive dependence on Keytruda poses a risk as the drug faces patent expiration in 2028 and biosimilar competition. AstraZeneca faces challenges with mature brands losing exclusivity and declining demand for some products.

Merck is actively pursuing acquisitions to prepare for Keytruda's patent expiration, while AstraZeneca has set targets for total revenues of $80 billion by 2030 and plans to launch 20 new medicines. The company believes many of these new medicines have peak-year revenue potential of over $5 billion.

AstraZeneca expects a rich catalyst path ahead with several high-value readouts due over the next 18 months. Merck's stock has risen 39.5% this year, making it slightly more attractive from a valuation standpoint than AstraZeneca.