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

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.

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