Shares in AstraZeneca dropped by nearly 3% at market open after a report that the drugmaker is in talks with oncology rival Bristol Myers Squibb (BMS) regarding a mega-merger deal.
According to the Financial Times (FT), which first reported the discussions, a tie-up would create one of the largest pharmaceutical companies in the world with a combined value of nearly $400bn. If it goes ahead, the deal will also rank amongst the largest ever in pharmaceutical M&A history.
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The FT stated that the structure of any possible deal was not yet known but that both cash and shares would feature.
An AstraZeneca spokesperson declined to comment on the report to Pharmaceutical Technology. BMS did not immediately respond.
Shares in London-listed AstraZeneca slumped by 2.7% at market open on 3 August following the media rumours, down from a close of £12,632 on 31 July.
AstraZeneca, the UK’s second most valuable listed company, has a market capitalisation of about £182bn ($245bn), while US-headquartered BMS is worth roughly $133.4bn.
In a research note, Citi analysts said a merger “would be a surprise” given AstraZeneca’s market-leading pipeline and its positive momentum in meeting 2030 revenue targets, though they did state that their portfolios are “somewhat complementary”.
The analysts added that BMS’ market capitalisation would provide it with “significant equity” in any future combined entity.
The reported discussions between the two companies come soon after AstraZeneca began trading ordinary shares on the New York Stock Exchange (NYSE) in February 2026. According to previous media reports, CEO Pascal Soriot had been considering delisting the drugmaker from the London Stock Exchange (LSE). A deal with BMS, which would extend both the company’s operations and footprint in the US, will only heighten concerns regarding the competitiveness of the UK pharmaceutical industry.
From the US perspective, the tie-up’s structure would need to align with President Trump’s domestic manufacturing agenda. The US government has been proactive in reducing the reliance on imports for medicines used in the country. As with other large-scale deals, any potential combination will likely need to pass US antitrust evaluations.
While 2026 has been associated with a significant increase in M&A activity, the last true mega-deal in the industry was Pfizer’s $43bn acquisition of Seagen in 2023. The largest deal in the past decade was conducted by BMS when it acquired Celgene for $74bn in 2019. Other large deals include AbbVie’s $63bn acquisition of Allergan in 2020 and Takeda’s $62bn merger with Shire in 2019.
However, mega-mergers between two major drugmakers have largely been consigned to the turn of the millennium. In 2000, Glaxo Wellcome and SmithKline Beecham combined to form GSK in a $76bn deal, a value that rises to $142bn when adjusted for inflation. AstraZeneca itself was formed by Sweden-based Astra merging with UK company Zeneca in a $30.4bn deal in 1998.
