Two numbers sit side by side and refuse to make sense together. The 10-K filed in February 2026 shows Merck & Co, the US company that trades as MSD outside the United States and Canada and is unrelated to Germany’s Merck KGaA, earning its fattest net margin in at least five years, with more than a quarter of every dollar of sales flowing to the bottom line. The stock, meanwhile, trades at a trailing price-to-earnings multiple that sounds alarming until you understand what is driving it: a single year of acquisition charges that temporarily crushed reported earnings, leaving the market staring at a distorted denominator. Strip those charges away and the underlying business looks nothing like a company in crisis. Yet the price behaves as if one is already here.
Merck has been one of American pharma’s most reliable compounders for a generation, built on a cancer immunotherapy called Keytruda that became the industry’s best-selling drug almost by accident. Then came the clock. Keytruda’s U.S. patent expires in December 2028, and the moment that date appeared on the horizon, the conversation about Merck collapsed into a single question: what happens when the engine stops? That question is legitimate. But the audit we owe readers is whether the price already assumes the worst answer, or whether the filings tell a different story.
The heart of it
The fiscal year 2025 10-K shows revenue, net margin, and free cash flow all at or near decade highs. The stock’s trailing multiple looks alarming, but that multiple is inflated by one-time acquisition charges, not by a deteriorating business. The real tension is not between a good company and a bad price: it is between a business that is still generating cash at full speed and a market that is pricing in the patent cliff as if it arrives tomorrow rather than in 2028.
What the filings actually show
Start with the income statement, because the headline numbers mislead in both directions. FY2025 revenue came in at $65.0 billion, up meaningfully from two years earlier, growing about as fast as a mature industrial economy. That is not a shrinking business. The net margin of 28.1% means that for every dollar Merck billed last year, roughly 28 cents survived after every cost, tax, and charge. A neighborhood pharmacy keeps perhaps three cents. This is a high-margin enterprise.
Free cash flow of $12.4 billion is the figure that matters most for the patent-cliff debate, because cash is what funds the replacement pipeline. Think of it this way: Merck generated enough cash last year to buy a mid-sized pharmaceutical company outright, and it has been doing so. Since 2023, the company has closed six acquisitions worth more than a billion dollars each, totaling roughly $39 billion, according to reporting by PharmaVoice. The honest caveat: those acquired products contributed only a sliver to 2025 sales, meaning the replacement engine is still warming up, not yet running.
Total debt is the shadow on that picture. At current cash generation, Merck is paying off roughly a quarter of its debt pile every year, which is manageable but leaves little room for error if the post-2028 revenue trough is deeper than management projects.
The Keytruda arithmetic
Keytruda and Gardasil together generated nearly three-fifths of Merck’s 2025 revenue, per pharmapatentcliff.com’s analysis. Keytruda alone contributed $31.7 billion. When U.S. exclusivity ends in December 2028, biosimilar competitors can enter and typically capture a large share of volume within two to three years. That is the cliff everyone is watching.
What is less discussed is the European complication. A Dutch court blocked sales of Keytruda’s subcutaneous formulation in eight European countries on October 7, 2026, due to a patent dispute. The subcutaneous version was Merck’s main tool for extending the product’s commercial life beyond the biosimilar window. Losing that lever in Europe, where exclusivity was supposed to run several years longer, tightens the timeline and removes a hedge the market had assumed was intact.
Against that, Merck’s pipeline is broader than the patent-cliff narrative suggests. Winrevair, the pulmonary arterial hypertension therapy added through the Acceleron acquisition, is already generating meaningful quarterly revenue, according to the 10-Q for the quarter ended June 30, 2026. First pivotal Phase 3 results for two oncology candidates, intismeran and sacituzumab tirumotecan, are being presented at the ESMO Congress starting October 23, per Merck’s investor calendar. Those readouts will tell the market whether the next wave of oncology revenue is real or still a slide deck.
What the price assumes
Per the BullScope valuation dataset (methodology available at bullscope.ai/methodology; price and revenue figures drawn from SEC filings and FactSet as of October 2026), Merck’s price-to-sales multiple sits at the 96th percentile of its own decade range. That is the mood, the premium the market is currently paying above what the math of filed revenues would historically justify. The price-to-earnings multiple, by contrast, sits almost exactly at the decade median on a normalized basis. Those two readings point in opposite directions: the earnings multiple says the market is calm, the sales multiple says it is paying a historically unusual premium for each dollar of revenue.
The resolution is that the market is not pricing in catastrophe on earnings, but it is pricing in a revenue story that requires the replacement pipeline to work. Merck’s updated guidance, issued on the August 4, 2026 earnings call, projects modest full-year 2026 revenue growth. Guggenheim, in an October 2026 note cited by Investing.com, described its outlook on the name as constructive. RBC Capital, in a separate note, cited a lower 2027 earnings outlook as a reason to revise its revenue assumptions downward. Neither view is endorsed here; readers can weigh both against the filed data. The analyst community is not panicking, but it is not unanimous either.
On a normalized earnings basis, the multiple sits near its decade median per the BullScope valuation dataset. The elevated price-to-sales multiple, by contrast, is consistent with a market that has embedded an assumption of pipeline success; whether that assumption is borne out is a question the filed data cannot yet answer. The ESMO presentations and the Q3 earnings call scheduled for October 29 are the next scheduled events at which the market will receive new evidence bearing on the pipeline assumption; the filed data available before those readouts is what this analysis reflects.
Reading the numbers
- Net margin 28.1% (FY2025): An operating margin is what survives each dollar of sales after every bill is paid. At 28 cents per dollar, Merck keeps nearly ten times what a typical retailer does. This matters because high margins fund the R&D that replaces expiring drugs. Source: 10-K, FY2025.
- Free cash flow $12.4 billion (FY2025): Free cash flow is what remains after the company pays for its factories, labs, and equipment. A household earning $100,000 and spending $70,000 on living costs has $30,000 free. Merck’s $12.4 billion is that surplus, available for acquisitions, dividends, or debt repayment. Source: 10-K, FY2025.
- Total debt $46.8 billion (FY2025): At current free cash flow, this takes roughly four years to retire in full, assuming no new deals. Every major acquisition adds to that timeline. Source: 10-K, FY2025.
- P/S ratio 5.5x, 96th percentile of own decade: A price-to-sales multiple is the price tag per dollar of annual revenue. Paying 5.5 times sales means a buyer is paying $5.50 for each dollar Merck earns in revenue, more than at 96 of every 100 points in the past decade. That premium is the market’s bet on pipeline success, not a reward for what has already been filed. Source: BullScope valuation dataset, methodology available at bullscope.ai/methodology; price and revenue figures drawn from SEC filings and FactSet as of October 2026.
- Keytruda $31.7 billion in 2025 revenue: That is roughly half the entire company’s sales from a single drug. A family whose income depends half on one employer understands the concentration risk. Source: pharmapatentcliff.com.
For the standing yardsticks on Merck & Co: the price tag, the filed record, and the four gauges, refreshed with each edition, see the BullScope Evidence Sheet: Merck & Co.
Sources
- Merck 10-K, FY2025 (SEC EDGAR)
- Merck 10-Q, Q2 2026 (SEC EDGAR)
- Merck Q2 2026 earnings call transcript
- Merck Q3 2026 earnings call announcement
- Guggenheim October 2026 note on Merck (Investing.com)
- PharmaVoice: Merck M&A and patent cliff strategy
- Pharmapatentcliff.com: Keytruda exclusivity timeline
- Trefis: Dutch court ruling on Keytruda SC, October 2026
Disclosure: BullScope holds no positions in any securities mentioned in this article. This article is published for general informational and educational purposes and is distributed to all subscribers without regard to individual circumstances. Nothing contained herein constitutes personalized investment advice, a solicitation, or a recommendation to buy or sell any security. Readers should conduct their own due diligence and consult a qualified financial adviser before making any investment decision.
