Tie-up would be one of the biggest pharmaceutical deals ever and create the world’s fourth-largest drugmaker

Britain’s biggest drugmaker AstraZeneca is in discussions to take over its US rival Bristol Myers Squibb in a deal that would create a near-$400bn (£300bn) pharmaceutical group.

AstraZeneca, run by longtime chief executive Pascal Soriot, is the second-biggest listed company in the UK, with a market value of nearly £196bn. BMS, headquartered in Princeton and known for its cancer treatments, is worth $133bn.

BMS’s UK research team is based at Moreton on the Wirral peninsula near Liverpool, while its commercial head office for the UK and Ireland is in Uxbridge.

A tie-up would be one of the biggest pharmaceutical deals ever, and create the world’s fourth-largest drugmaker by market value. The talks were first reported by the Financial Times.

A deal would expand AstraZeneca’s presence in the US, where it is already investing $50bn in research and manufacturing by 2030.

While talks have been held in recent months, there is no certainty that a deal will be concluded, according to sources.

AstraZeneca, headquartered in Cambridge, was formed in 1999 from the merger of the Swedish company Astra AB and the UK company Zeneca Group. Zeneca had been spun off from Imperial Chemical Industries five years earlier.

Under Soriot, the FTSE 100 company fended off a hostile bid from its US rival Pfizer in 2014 that valued AstraZeneca at almost £70bn. He then successfully rebuilt the company’s drug pipeline with cancer immmunotherapies – drugs that harness the body’s immune system to fight tumours – and other treatments.

A week ago, AstraZeneca said it was confident of hitting its growth targets for 2030, by which it expects to achieve $80bn (£60bn) in annual sales, up from $59bn last year, despite the surprise failure of Wainua, one of its leading heart disease drugs in development. Soriot said the company must move at “Chinese speed” to ensure it does not fall behind competitors.

A few days later, BMS beat Wall Street expectations with its second-quarter results and lifted its 2026 outlook. It made revenues of $12.97bn during the quarter, up 5% on a year earlier, excluding currency movements.

AstraZeneca declined to comment. BMS has been contacted.