Merck & Co. (MRK)

Merck is an oncology powerhouse whose Keytruda immunotherapy made up 49% of 2025 sales ($31.7bn) — an extreme concentration. The rest (Gardasil/Capvaxive vaccines, WINREVAIR +88%, Animal Health, declining diabetes) barely moves consolidated growth (+1% in 2025). The moat is patents + R&D + vaccine manufacturing, but with a scheduled erosion: Keytruda's U.S. patent falls in 2028-2029. The strategy is to rebuild the moat before that happens, with the subcutaneous Keytruda + a pipeline bought with >$60bn of M&A.

A pharmaceutical company is valued on P/E over adjusted earnings — GAAP plus non-economic acquisition-intangible amortization and excluding one-time acquired-IPR&D charges. ⚠️ With Merck this is critical: both GAAP ($7.28 in 2025) and Merck's own 'non-GAAP' (−$1.28 in Q1'26) are depressed by M&A-related acquired-IPR&D charges (Cidara $3.62/share, Terns $2.35/share) — Merck, unlike other pharmaceutical companies, runs those charges through its non-GAAP, which is why FY2026 guidance ($5.04-5.16) is misleadingly low. Adding them back (plus intangible amortization), normalized earnings are ~$8.8/share, and at ~$155 the P/E is ~120× — the floor of the pharma band, not the ~25× the guidance implies.

The base scenario models the cliff: earnings grow through ~2028 (Keytruda + WINREVAIR + Capvaxive) and then flatten as the biosimilar and IRA price-setting erode U.S. Keytruda, offset by the subcutaneous Keytruda + the pipeline. Net: earnings stay roughly flat over five years (~$8.8 → ~$9.6), at an exit multiple of 14× (the pharma floor, given the cliff). That gives ~$141/share → a total return of +1%/year, of which the dividend (2.7%) is the larger part.

No margin of safety: at this price capital is preserved, but it is not bought below its value. The stock re-rated +64% in 2026 (from the $77 low during the cliff + China panic) to ~$155 as visibility into the transition improved — so the margin has already compressed. At ~120× normalized earnings (the pharma floor), the market is pricing in a pipeline that offsets the Keytruda patent cliff. The verdict is Preserves value: reasonably valued for that offsetting transition, with a dividend (2.7%) carrying the return and little additional margin. The adverse scenario (the cliff dominates and the pipeline disappoints, as with Pfizer/Bristol Myers at 8-10×) takes the value well below; the favorable one (Qlex retains + WINREVAIR and the ADCs take off + re-rating) is clear upside. The asymmetry is balanced, with the pipeline as the swing factor — this is a bet on execution of the transition, not a bargain with ample margin.

Three things. Subcutaneous Keytruda (Qlex) — its conversion/retention rate (a 30-40% target) is the #1 determinant of how much of the franchise survives the biosimilar; high retention changes the cliff's math. The pipeline — WINREVAIR (+88%, on track to blockbuster), Capvaxive, the Daiichi ADCs (patritumab, ifinatamab, raludotatug — with breakthrough-therapy designation) and the ~80 Phase 3 programs: whether they generate the replacements Merck promises (~$70bn of opportunity). And Gardasil/China — whether shipments resume (currently at $0) or the collapse is permanent, with the securities litigation as a tail risk. The Keytruda cliff (Dec-2028 biosimilar + Jan-2029 IRA pricing) is the date that defines everything: if the pipeline + Qlex offset it, Merck at this price is reasonable; if not, the value is much lower.