AstraZeneca's rumoured $400bn (£300bn) takeover of US rival Bristol Myers Squibb appears to have been dropped almost as quickly as it emerged, leaving shareholders none the wiser about what was actually discussed. Neither company has explained the talks, so it's unclear whether this was a tentative approach or a more serious plan abandoned partly due to lukewarm investor reaction, but the episode raises questions about whether AstraZeneca chief executive Sir Pascal Soriot is open to large-scale mergers despite his long-standing preference for organic growth.

Shares in the UK firm fell 9% on Monday after the Financial Times reported preliminary talks, before Reuters said on Wednesday there were no ongoing discussions, prompting a partial recovery. Under Soriot's 14-year tenure, AstraZeneca has grown by investing in its own drug pipeline rather than pursuing debt-fuelled acquisitions, and he has reaffirmed confidence in hitting $80bn revenue by 2030, making a deal of this scale — dwarfing the $39bn Alexion purchase in 2021 — appear at odds with that strategy, especially given BMS's looming patent cliff on a key cancer drug.