In this article, we break down the 5 Best Medicine Stocks That Could Make Investors 100% Richer. For investors looking for the complete list, you can explore our full report on the 10 Best Medicine Stocks That Could Make Investors 100% Richer.
5. Merck & Co. Inc. (NYSE:MRK)
Merck & Co., Inc. (NYSE: MRK) ranks fifth because few pharmaceutical companies possess a commercial medicine as powerful as Keytruda. The cancer immunotherapy has become one of the highest-selling medicines in history and is approved across numerous tumor types and treatment settings. It has helped establish Merck & Co., Inc. (NYSE: MRK) as a leader in oncology and provides the cash flow needed to finance acquisitions, clinical trials and expansion into other therapeutic categories. During the first quarter of 2026, total company sales increased 5% to $16.3 billion.
Keytruda and its subcutaneous formulation, Keytruda QLEX, produced approximately $8 billion in first-quarter sales, representing growth of 12%. The newer Keytruda QLEX formulation contributed $128 million and could become strategically important because subcutaneous delivery may reduce treatment time compared with intravenous infusion. Merck & Co., Inc. (NYSE: MRK) also received a meaningful contribution from Winrevair, its treatment for pulmonary arterial hypertension. Winrevair generated $525 million in quarterly revenue, increasing 88% from the previous year. Animal-health sales rose 13% to $1.8 billion, providing diversification outside human pharmaceuticals.
The central risk is obvious: Keytruda is so successful that reducing dependence on it will be extremely difficult. The franchise produced $31.7 billion in sales during 2025, representing nearly half of total company revenue. Patent expirations expected later in the decade could eventually introduce biosimilar competition, making pipeline diversification one of the most important questions facing the company. Merck & Co., Inc. (NYSE: MRK) is addressing that challenge through Winrevair, newer vaccines, acquisitions, combination therapies and more convenient Keytruda formulations. The company reported positive results from 18 Phase 3 trials during 2025, showing that the pipeline is not empty. Nevertheless, investors must determine whether those programs can collectively replace even part of Keytruda’s enormous revenue base. Merck & Co., Inc. (NYSE: MRK) earns a top-five position because of its profitability, oncology leadership and improving product diversification, but the Keytruda patent cliff prevents a higher ranking.
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