AstraZeneca should stick to its winning formula. It doesn’t need a $400bn US mega-merger

The Anglo-Swedish drugmaker’s flirtation with a grand combo with US group Bristol Myers Squibb is baffling AstraZeneca shares fall 8.9% over merger talks with US cancer drug firm Sir Pascal Soriot, chief executive of AstraZeneca, starts with huge credit in the bank, obviously. His long tenure has been a triumph, starting with the against-the-odds victory over Pfizer’s charmless accountants in 2014. The $39bn (£29bn) purchase of Alexion in 2021 looked a little over-priced at the time, but you could see how it sat well with Soriot’s sermons on the importance of backing science. The deal got AZ into the field of medicines for rare diseases, which should offer decades of growth. A flirtation with a grand combo with US group Bristol Myers Squibb (BMS), by contrast, looks baffling. What’s the big idea here? Why bet the farm on a $400bn (£300bn) mega-merger? The first challenge would be how to rip out a few billions-worth of costs to justify the takeover premium. Soriot has normally viewed such corporate exercises as anti-patient. And why do it now? In the absence of a statement by AZ – not even to confirm the basic accuracy of the FT’s initial report of talks with BMS – o