Merck & Co., Inc. (MRK) Stock Analysis

Merck’s primary competitive advantage is its leadership in oncology, anchored by Keytruda, which generated $31.7 billion in 2025—nearly half of company revenue and more than triple the sales of Bristol-Myers Squibb’s Opdivo. Keytruda’s broad label coverage, first-mover status in immuno-oncology, and entrenched physician adoption create high switching costs. The recent launch of Keytruda Qlex (subcutaneous formulation) extends the franchise’s lifecycle and patient convenience, though U.S. patent expiry in 2028–2029 poses a looming risk.

Merck’s diversification into vaccines (Gardasil), animal health, and a growing cardiovascular portfolio (Winrevair, LIPFENDRA) provides additional revenue streams and operational scale. Its vaccine business benefits from manufacturing know-how and global distribution, while animal health offers resilience against human drug patent cliffs.

Relative to Eli Lilly and Novo Nordisk, Merck lacks exposure to the high-growth obesity/diabetes market, which limits its near-term growth profile. However, Merck’s pipeline is broad, with over 80 Phase 3 studies and a track record of rapid, science-driven business development—evidenced by recent acquisitions in hematology (Terns), respiratory (Verona), and infectious disease (Cidara).

Merck’s culture emphasizes scientific rigor and speed in decision-making, supporting its “One Pipeline” strategy. While its moat is wide—rooted in intellectual property, scale, and brand—its durability will be tested as Keytruda faces biosimilar competition post-2028.