Big pharmaceutical companies are buying. Not out of greed alone, but because in today’s capital-intensive, science-driven market, acquisitions are often the fastest and sometimes the only way to refill pipelines, buy transformative platforms (cell & gene, radiopharma, AI-enabled discovery), and buy market positions in hot therapeutic franchises such as oncology and weight-loss/metabolic medicine. That explains why Pfizer, AstraZeneca and Eli Lilly have been particularly acquisitive across 2023–2025, each pursuing different strategic bets to defend growth, diversify risk, and capture future cash flows. Below we unpack the data, the rationale, the risks, and historical parallels that show why these deals make sense and where they can fail.
The M&A backdrop: fewer but bigger and more strategic deals
M&A in life sciences has been volatile since the pandemic. Deal volume fell from pandemic highs, yet values were concentrated in big, strategic transactions as buyers pursued late-stage or de-risked assets. Industry trackers call 2024 a “reset year”: deal value dropped materially versus 2023 even as companies retained large “firepower” for transactions, and the market moved toward smaller, milestone-based and earlier-stage investments.
Two ways to read recent numbers: EY highlights a sharp fall in total deal value in 2024 as buyers stepped back from mega-deals and focused on bolt-ons and creative deal structures, while McKinsey shows that, when measured differently, aggregate deal value (driven by a handful of big transactions) remained high into 2024. Both narratives are consistent: buyers selectively paid up for what they truly wanted while otherwise shifting to smaller, targeted plays.
What Pfizer, AstraZeneca and Eli Lilly actually bought (2023–2025): the key deals
Pfizer’s headline move was the seismic acquisition of Seagen in March 2023 for about $43 billion, a bet to bulk up in oncology with ADCs and antibody-drug conjugate capability. Pfizer continued to invest in oncology and metabolic spaces with follow-on buys: in 2025 it announced a deal to acquire Metsera (obesity & cardiometabolic focus) for roughly $4.9 billion. These moves show Pfizer’s twin priorities: build a steady oncology franchise and diversify into high-growth cardiometabolic areas.
AstraZeneca has doubled down on oncology and cell therapies. In 2024 it closed the acquisition of Fusion Pharmaceuticals (radioconjugates) for about $2.4 billion and in 2025 agreed to buy EsoBiotec (in-vivo cell therapy) for up to $1 billion, moves meant to broaden its next-generation oncology toolset and shorten time-to-patient for cell therapies. AstraZeneca’s play mirrors its 2021 purchase of Alexion (~$39 billion) to enter rare diseases, an earlier, successful strategic pivot toward specialized, high-margin franchises.
Eli Lilly’s deal pattern is different: a systematic build around metabolic/obesity leadership and targeted expansion into oncology, gene editing and radiopharma. Since 2023 Lilly has completed multiple buy-ins and licensing arrangements, from Versanis ($1.925B, 2023) to Sigilon (~$310M, 2023), then stepping up to Scorpion Therapeutics (up to $2.5B, 2025) and gene-editing bets such as Verve (roughly $1B in 2025). These moves both extend Lilly’s oncology and cardiovascular pipelines and leverage its runaway success in GLP-1, class obesity/diabetes drugs to fund and justify buyouts.
Why managements believe these buys will pay
Three consistent rationales drive big pharma M&A:
- Immediate revenue or near-term optionality. Buying late-stage assets or companies with proven clinical data shortens the time to market compared with internal R&D. Seagen (ADCs) offered Pfizer marketed products and strong late-stage assets; Alexion gave AstraZeneca a sizeable, specialized revenue stream.
- Portfolio and modality expansion. Acquisitions can instantly add new modalities (radioconjugates, cell-in-vivo platforms, gene editing), positioning incumbents to capture next-gen therapies that are expensive and slow to build in-house. AstraZeneca’s Fusion and EsoBiotec buys are textbook examples.
- Financial engine from blockbuster franchises. Lilly’s extraordinary GLP-1 success created both the cash flow and investor goodwill to fund aggressive BD—managements reinvest profits from blockbusters into future growth buckets (oncology, cardio, gene therapies). This reallocation of capital is deliberate: use today’s winners to seed tomorrow’s.
Are they right? The bullish case and the counterarguments
The bullish case is simple and historically validated: well-executed acquisitions can transform companies. Pfizer’s 2009 Wyeth buy (about $68B) reshaped its vaccine/biologics capabilities and is still cited as a defining strategic step; AstraZeneca’s Alexion move created reliable rare-disease revenues that helped fund later growth.
But acquisitions can misfire. Overpaying for late-stage assets that fail pivotal trials, bungled integrations that destroy value, regulatory or antitrust blocks, and policy risks (e.g., drug-pricing reform) are real. Pfizer’s Wyeth integration required heavy financing and divestitures; AstraZeneca’s Alexion has faced legal and reputational challenges tied to pricing and patents for Soliris, illustrating post-deal legal/regulatory headwinds.
The counterargument to today’s M&A spree: many of the pricey targets are in crowded fields (oncology, GLP-1/metabolic), where multiple buyers may bid up prices beyond eventual commercial returns. Buyers also face tougher antitrust scrutiny and, in the U.S., policy shifts such as the Inflation Reduction Act that change pricing dynamics and ROI horizons. EY and McKinsey both warn that while companies have cash, they need more disciplined, therapeutic-area–focused M&A to deliver outsized returns.
Key risks — what can go wrong
- Clinical failure risk. A bought asset can still fail in late-stage trials, times when even expensive acquisitions write down large sums.
- Integration & culture risk. Small biotech cultures don’t always survive assimilation into large pharma; talent and scientific edge can be lost.
- Regulatory & antitrust risk. Regulators may force divestitures or block deals; government policies on drug prices can compress margins.
- Valuation & competitive risk. Paying too high a premium in a bidding war reduces upside; multiple buyers chasing the same modality (e.g., ADCs, GLP-1 derivatives, PI3K inhibitors) inflates cost.
- Reputational/legal risk. Pricing or IP behaviors post-acquisition can trigger lawsuits and political backlash, as AstraZeneca’s Alexion unit recently experienced.
Practical takeaways for management and investors
- Focus deals around core strengths. McKinsey’s research shows “external-innovation outperformers” that specialize achieve much better returns. Buy where you can integrate fast and execute clinically.
- Structure deals to share risk. Milestone payments, royalties and CVRs are not just deal jargon, they’re practical ways to bridge valuation gaps and protect buyers. EY notes 2024’s pivot to milestone-linked structures.
- Don’t outsource governance: insist on rigorous post-merger integration plans that protect science teams and data flow.
Bottom line
Big pharma’s obsession with acquisitions is rational: biologics, cell & gene therapies, radiopharma and other modalities are expensive to create and slow to scale internally. Acquisitions accelerate market entry and can transform a company’s future revenue mix, but only if valuations are disciplined, integration preserves scientific value, and buyers manage regulatory and pricing uncertainty. Pfizer, AstraZeneca and Eli Lilly have bet where they see durable scientific and commercial advantages, oncology for Pfizer and AstraZeneca, metabolic and targeted oncology/gene editing for Lilly. History shows acquisitions can make or break giants; the coming years will tell whether the current wave creates the same durable winners or a cautionary tale of overpaid science.