Merck reportedly ready to the splits as Keytruda patent cliff looms. Market shrugs

Merck is reportedly splitting its human-health operations into two divisions — a cancer unit anchored by Keytruda and a non-cancer unit — as it braces for Keytruda patent expiries in 2028. Keytruda generated more than $30 billion in sales in 2025, and the reorganisation, following active deal-making to rebuild the pipeline, aims to provide focused management to defend and extend the franchise; investors took a muted view because the split does not by itself address the looming revenue risk from biosimilar competition.

Analysis

Market structure: The split codifies a two-speed exposure — an oncology franchise centered on Keytruda ($30bn sales in 2025) facing a 2028 patent cliff, and a non-oncology portfolio with steadier cash flows. Direct beneficiaries: biosimilar manufacturers and CMOs (e.g., Sandoz/Novartis, selected CDMOs) and diversified pharma (Pfizer) that can manufacture or market biosimilars; direct losers: MRK equity holders if Keytruda share falls 30–50% within 2–4 years and credit spreads reprice. Pricing power in PD‑1 will compress; expect 20–40% price erosion in markets with immediate biosimilar entry and slower declines in protected markets.

Risk assessment: Tail scenarios include a successful Keytruda extension or blocking litigation (positive shock) or an accelerated biosimilar approval wave + rapid tendering (negative shock) — probabilities ~10–20% each but P&L asymmetric. Timing matters: immediate (days–weeks) — limited stock reaction; short term (3–12 months) — pipeline deals/M&A and guidance revisions; long term (2028–2030) — material revenue loss. Hidden dependencies: country-by-country patent expiries, royalty streams, and divestiture mechanics that could seed carve‑out value or liabilities.

Trade implications: Prefer defensive hedges and relative-value plays (see decisions). Use 24–36 month put spreads on MRK sized to capture a 20–35% downside by 2029; pair short MRK vs long NVS/PFE to capture biosimilar upside. If owning MRK, implement 9–15 month collars to cap near-term volatility and revisit after the 2026 investor day and any announced M&A (60–180 day windows).

Contrarian angles: The market’s muted reaction likely understates structural risk — splits don't replace lost cash flows; downside could be underpriced if Keytruda competitors or biosimilars take >30% share by 2029. Conversely, the split could unlock a re‑rating of non‑oncology assets (10–20% multiple expansion) if management executes tuck‑ins; historical parallel: Pfizer’s post‑Lipitor diversification via deals. Unintended consequence: distraction from R&D execution, slowing of succession plans, or value destruction through overpriced M&A.

Key Decisions for Investors

• Initiate a modest 2–3% portfolio short exposure to MRK via a 24–36 month put spread (buy 24–36 month ATM or 10–20% OTM puts, finance by selling further OTM puts) sized to profit if MRK falls 20–35% by 2029; add to the position on confirmation of the formal split or any 2026 guidance cut.
• Establish a 1–2% long position in NVS (Sandoz exposure) or PFE as a pair trade: short MRK equal notional vs long NVS/PFE (net 0–1% portfolio risk) to capture biosimilar upside; target relative outperformance of 10–20% by end‑2027 and trim at 20% gain.
• If you hold MRK, implement a 9–15 month collar: buy a 15% OTM put and sell a 25% OTM call to limit near‑term downside to ~15% while capping upside; reassess at the 2026 investor day or within 60–90 days of M&A announcements.
• Watch four catalysts over the next 60–180 days and act: (1) formal split details and capital allocation plan, (2) 2026 investor day timelines for divestitures, (3) any announced Keytruda patent litigation settlements/extensions, and (4) major pipeline acquisitions — increase shorts if guidance is cut or biosimilar launch windows are confirmed for 2028–2029.