AstraZeneca shares slump after it agrees $39bn Alexion buyout

Britain's biggest drugmaker offers 45% premium for shares of US rare diseases specialist

AstraZeneca shares fell sharply after it agreed to a $39bn (29bn) takeover of the US rare diseases specialist Alexion, the biggest deal in its history if it goes ahead.

Investors sold off shares in the Anglo-Swedish drugmaker over fears it was paying too much for Alexion in the stock-and-shares deal. The offer price of $175 a share represents a 45% premium on Alexion's closing price before the deal was announced. To finance the deal, AstraZeneca has secured a $17.5bn bridging loan.