AstraZeneca shares drop 7% after report on $400 billion merger talks with

AstraZeneca shares dropped as much as 7% after a report that the U.K.’s largest drugmaker was in talks with U.S. peer Bristol Myers Squibb over a megadeal that, if completed, could value the companies at roughly $400 billion.

AstraZeneca declined to comment. Bristol Myers Squibb didn’t immediately respond to a request to comment outside of normal working hours.

The companies have discussed a potential merger over several months, the Financial Times reported on Sunday. It would be one of the biggest deals ever.

AstraZeneca’s London-listed shares were last seen trading 6.5% lower in early morning trading, weighing on the U.K.’s blue-chip index FTSE 100, which was largely flat.

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