Merck & Co. Inc. (NYSE: MRK)

Merck is a top-five global pharmaceutical company, driven primarily by Keytruda — the world's best-selling drug, with over $25 billion in annual sales. Total company revenue exceeded $60 billion in 2023. Beyond oncology, Merck has strong franchises in vaccines (Gardasil), animal health (the largest in the industry), and cardiovascular. The Rahway, New Jersey-based company operates in more than 140 countries.

Pharmaceutical sales dominate, with Keytruda alone accounting for over 40% of total revenue — a concentration that's both a strength and a vulnerability. Animal health (Merck Animal Health) provides diversification that peers don't have. R&D spending exceeds $14 billion annually, focused on extending Keytruda's franchise and building the next wave.

Merck's roots trace to a German pharmacy founded in 1668 — making it one of the oldest pharmaceutical companies in existence. The U.S. entity was established in 1891 and separated from the German parent during World War I. Merck developed the first measles vaccine in 1963 and the first statin (Mevacor) in 1987. Keytruda's FDA approval in 2014 transformed the company's trajectory entirely.