Munger Mode rating: 2 out of 5 — Sell. Our own rating from the research report below, on business quality first: moat durability and management, with price separating the top three.
Authors: Warren Buffett & Charlie Munger Charlie and I have spent considerable time thinking about Merck. It is a venerable enterprise — 134 years old, a trusted brand in medicine, and the home of one of the most extraordinary commercial successes in pharmaceutical history: Keytruda. We respect what they have built. But respect and investment are different propositions. Our job is not to admire businesses; it is to identify ones whose competitive advantages will compound capital for decades, run by people we trust, available at sensible prices. Merck flunks the first test. Its dominant moat — patent protection on Keytruda — has a known expiration date in 2028 in the U.S., and Keytruda accounts for roughly half of total company revenue. A "moat" with a court-mandated end date is not a moat in the Buffett-Munger sense; it is a toll bridge with a demolition order pinned to it.
Recent filings analysed: 8-K (2026-08-04), 8-K (2026-05-28), 8-K (2026-05-22), 10-Q (2026-05-04).
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