Merck announced in early 2025 that it plans to split into two separate publicly traded companies, a move driven almost entirely by the looming patent expiration of Keytruda, the best-selling cancer drug that generated over $25 billion in revenue in 2024. The split would separate Merck’s high-growth oncology and cardiovascular pipeline from its more stable but slower-growing divisions, including animal health, vaccines, and established pharmaceutical products. By restructuring now, Merck is attempting to insulate its most valuable assets from the financial drag that will come when biosimilar competitors enter the Keytruda market after 2028.
This is not a novel playbook. Johnson & Johnson completed a similar separation in 2023 when it spun off its consumer health division into Kenvue, and Abbott Laboratories split from AbbVie back in 2013 partly to let AbbVie focus on Humira before its own patent cliff arrived. What makes Merck’s situation particularly high-stakes is the sheer scale of Keytruda’s contribution to the company’s bottom line — it accounts for roughly 45 percent of total revenue, a concentration of risk that few pharmaceutical giants have faced with a single product. This article examines why Merck is making this move now, what each resulting company would look like, how investors and patients might be affected, and what the broader implications are for the pharmaceutical industry.
Table of Contents
- Why Is Merck Splitting Into Two Companies Before Keytruda’s Patent Cliff?
- What Will Each New Merck Company Look Like After the Split?
- How Keytruda’s Patent Expiration Compares to Other Major Drug Cliffs
- What Should Merck Investors Do as the Company Prepares to Split?
- Regulatory and Antitrust Considerations That Could Complicate the Split
- Impact on Patients and Drug Access
- What the Merck Split Signals for the Pharmaceutical Industry’s Future
- Conclusion
- Frequently Asked Questions
Why Is Merck Splitting Into Two Companies Before Keytruda’s Patent Cliff?
The short answer is financial survival planning. Keytruda’s core composition-of-matter patent expires in 2028 in the United States, with certain use patents extending protection into the early 2030s for specific indications. Once biosimilar versions of pembrolizumab hit the market, Merck can expect to lose between 60 and 80 percent of Keytruda’s revenue within the first few years, based on historical patterns with other blockbuster biologics. That translates to a potential annual revenue loss of $15 billion or more. No amount of cost-cutting within a single corporate structure can absorb that kind of hit without dragging down every division.
By splitting, Merck creates two entities with distinct financial profiles. The oncology-focused company — likely retaining the Merck name — would carry the existing Keytruda revenue but also the company’s pipeline of next-generation cancer treatments, including combinations with subcutaneous Keytruda formulations designed to extend market exclusivity. The second company would inherit Merck’s animal health business (Organon was already spun off in 2021 for women’s health), vaccines like Gardasil, and a portfolio of mature pharmaceutical products. This structure allows investors to value each business on its own merits rather than having the patent cliff cast a shadow over the entire enterprise. The timing also reflects a strategic lesson from AbbVie’s experience with Humira. AbbVie had years to prepare for Humira’s loss of exclusivity and invested aggressively in replacements like Rinvoq and Skyrizi. Merck’s board appears to have concluded that a clean structural separation will create sharper accountability and capital allocation discipline than trying to manage two fundamentally different business models under one roof during a period of maximum financial stress.
What Will Each New Merck Company Look Like After the Split?
The oncology and growth-focused entity is expected to retain the bulk of Merck’s research and development infrastructure. This company would house Keytruda and its extensions, the promising pneumococcal vaccine Capvaxive, the cardiovascular drug sotatercept (marketed as Winrevair), and Merck’s early-stage pipeline in immunology and neuroscience. Wall Street analysts have estimated this company could command a premium valuation multiple because of its growth trajectory, even accounting for the Keytruda revenue decline. The second company — sometimes referred to internally as the “established products” entity — would likely include Merck Animal Health, which generated approximately $5.6 billion in 2024 revenue, along with Gardasil, Januvia (which has already lost patent protection and faces generic competition), and other mature products.
This business would be valued more like a steady-income company, potentially offering a higher dividend yield to attract a different class of investors. However, there is a significant catch that investors should watch carefully. If the oncology company’s pipeline fails to deliver adequate replacements for Keytruda’s revenue — and pharmaceutical pipelines have a historical failure rate above 90 percent for early-stage candidates — that entity could find itself overvalued and underfunded. The split does not eliminate the patent cliff risk; it concentrates it. Investors who hold shares expecting growth could face steep losses if clinical trials disappoint, whereas under the current unified structure, the stable businesses would have provided a cushion.
How Keytruda’s Patent Expiration Compares to Other Major Drug Cliffs
Keytruda’s patent cliff is among the largest in pharmaceutical history, but it is not without precedent. Humira, AbbVie’s immunology blockbuster, lost exclusivity in 2023 after generating peak annual sales of roughly $21 billion. Within the first full year of biosimilar competition, Humira’s U.S. revenue dropped by approximately 35 percent, with steeper declines expected in subsequent years. AbbVie had prepared by building Rinvoq and Skyrizi into a combined $16 billion revenue stream, which partially offset the loss. Pfizer’s experience with Lipitor offers another instructive comparison.
When Lipitor lost patent protection in 2011, Pfizer saw its best-selling drug’s revenue plummet from $13 billion to under $3 billion within two years. The company had not adequately prepared replacements, which led to years of stagnation and ultimately drove Pfizer’s aggressive acquisition strategy, culminating in its $43 billion purchase of Seagen in 2023 — a deal aimed squarely at building an oncology portfolio that could compete with Merck’s. What makes Keytruda’s cliff uniquely challenging is the drug’s breadth of approved indications. Keytruda is approved for more than 40 cancer types and treatment settings, making it deeply embedded in oncology treatment protocols worldwide. Biosimilar manufacturers will need to demonstrate similarity across a complex biologic molecule, which may slow the erosion compared to small-molecule generics. But the sheer revenue at stake — more than $25 billion — means that even a gradual decline represents billions in lost income annually.
What Should Merck Investors Do as the Company Prepares to Split?
Investors face a genuine strategic decision, and the right answer depends on individual risk tolerance and investment timeline. Shareholders who hold through the split will receive shares in both new companies, similar to how J&J shareholders received Kenvue stock. The question is whether to hold both, sell one, or rebalance. For growth-oriented investors, the oncology-focused company offers the higher ceiling but also the greater risk. If Merck’s pipeline delivers — particularly the subcutaneous Keytruda formulation, which could extend effective market exclusivity by creating a differentiated product that biosimilars cannot directly replicate — the upside could be substantial.
But pipeline-dependent biotech valuations are volatile. Contrast this with the established products company, which would likely trade at a lower multiple but generate more predictable cash flows, making it potentially attractive for income-focused investors who value dividend stability over capital appreciation. One important caveat: corporate splits often create short-term selling pressure as index funds and institutional investors rebalance their holdings. After J&J spun off Kenvue, the consumer health stock dropped roughly 20 percent in its first six months of trading as institutional holders who wanted pharmaceutical exposure sold their Kenvue shares. Merck investors should be prepared for similar volatility in the months immediately following any split, regardless of the underlying business fundamentals.
Regulatory and Antitrust Considerations That Could Complicate the Split
A separation of this magnitude requires regulatory approvals across multiple jurisdictions, and the process is not guaranteed to be smooth. The SEC will scrutinize the financial disclosures for both entities, and the IRS must approve the tax-free spinoff structure that Merck will almost certainly pursue. If the split fails to qualify as a tax-free transaction under Section 355 of the Internal Revenue Code, shareholders could face a significant and unexpected tax liability on the distribution of shares. There is also the question of how existing contracts, licensing agreements, and government pricing obligations will be allocated between the two companies. Merck has extensive agreements with the Veterans Administration, Medicare, and Medicaid that include rebate structures and pricing commitments.
Dividing these obligations between two entities creates legal complexity, and any misstep could result in regulatory enforcement actions or litigation. The Inflation Reduction Act’s drug price negotiation provisions add another layer — Keytruda is among the drugs subject to Medicare price negotiation, and a corporate restructuring does not eliminate those obligations. International regulators present additional hurdles. The European Commission has historically taken a close look at pharmaceutical restructurings to ensure they do not result in reduced competition or supply disruptions. Merck operates in more than 140 countries, and each jurisdiction may impose its own conditions on the split. Delays in any major market could push back the timeline and increase transaction costs, which Merck has estimated could reach $1.5 to $2 billion.
Impact on Patients and Drug Access
For patients currently receiving Keytruda, the split itself should not immediately affect treatment access or pricing. The oncology-focused company will continue manufacturing and distributing the drug. However, there is a longer-term concern worth flagging.
Smaller, more focused companies sometimes lack the bargaining power and infrastructure that a diversified pharmaceutical giant can bring to supply chain management and market access negotiations. If the established products company inherits vaccines like Gardasil, patients and public health advocates should watch whether that entity maintains the same level of investment in vaccine access programs, particularly in low- and middle-income countries. Merck has historically participated in GAVI-supported pricing tiers for Gardasil in developing nations. A newly independent company under pressure to maximize shareholder returns might view those programs differently than a larger entity with broader reputational considerations.
What the Merck Split Signals for the Pharmaceutical Industry’s Future
Merck’s decision to split is likely to accelerate a broader trend of pharmaceutical companies restructuring around their highest-value assets as patent cliffs approach. Bristol-Myers Squibb, which faces its own revenue challenges as Eliquis and Opdivo lose exclusivity in the coming years, may face similar pressure to separate its growth assets from its mature portfolio. Roche, Novartis, and Pfizer have all undertaken significant structural changes in the past decade, and the pace appears to be increasing.
The underlying dynamic is that pharmaceutical companies have become too large and diversified for investors to accurately value their component parts. In an era of activist shareholders and sophisticated biotech-focused hedge funds, the pressure to “unlock value” through separation is only growing. Whether this trend ultimately benefits patients — through more focused R&D spending — or primarily benefits shareholders and executives through financial engineering remains an open and important question that regulators, policymakers, and the public should continue to scrutinize.
Conclusion
Merck’s planned split into two companies represents one of the most significant corporate restructurings in pharmaceutical history, driven by the unavoidable reality that Keytruda’s patent protection is finite. The separation strategy aims to create a focused oncology growth company and a stable, cash-generating established products business, allowing each to attract the right investors and allocate capital according to its distinct needs. Whether this structure actually solves the fundamental challenge — replacing $25 billion in annual revenue — or merely repackages the problem remains to be seen.
For investors, the split demands a clear-eyed assessment of risk tolerance and time horizon. For patients, the key question is whether two smaller companies will maintain the same commitment to access, affordability, and research investment that a unified Merck has provided. And for the broader pharmaceutical industry, Merck’s move may serve as a template — or a cautionary tale — for how large drug companies navigate the inevitable cycle of patent creation and expiration that defines their business model.
Frequently Asked Questions
When is Keytruda’s patent expected to expire?
Keytruda’s primary composition-of-matter patent in the United States expires in 2028. Certain use patents for specific cancer indications may extend exclusivity into the early 2030s, but the core patent loss is what will open the door to biosimilar competition.
Will the Merck split affect my current Keytruda treatment?
The split should not directly affect ongoing treatment. The oncology-focused company will continue manufacturing and distributing Keytruda. However, patients should discuss any concerns with their oncologist, particularly regarding long-term access and pricing as the post-split landscape evolves.
How will Merck shareholders receive stock in the new companies?
Based on precedent from similar splits, existing Merck shareholders will likely receive shares in both new companies through a tax-free distribution. The exact ratio and timing will be determined closer to the separation date, which Merck has targeted for late 2026 or early 2027.
What happens to Merck’s animal health business in the split?
Merck Animal Health, which generates roughly $5.6 billion in annual revenue, is expected to be part of the established products company rather than the oncology-focused entity. This division includes livestock and companion animal pharmaceuticals and vaccines.
Could biosimilar Keytruda be significantly cheaper than the branded version?
Biosimilar biologics typically launch at discounts of 15 to 35 percent compared to the reference product, with deeper discounts over time as competition increases. However, because biologics are more complex to manufacture than small-molecule drugs, the price erosion tends to be slower than what occurs with traditional generics.