The British drugmaker on Saturday announced it's buying Alexion Pharmaceuticals for $39 billion in cash and stock.

The U.

S biotech firm makes treatment for rare immune diseases.

AstraZeneca CHIEF Pascal Sorry Oh told reporters on Saturday that the company's biggest ever purchase was the result of exclusive talks and added that no competitive bidder was involved.

Sorry, oh once AstraZeneca to diversify from its fast growing cancer business.

But despite recent speculation about big mergers, some commentators say the election deal is probably not what shareholders were expecting.

AstraZeneca has been busy pushing the group's fast growing cancer business on rolling out a vaccine for Covert 19, while Election specializes in diseases that affect a small number of people.

Yet some say the timing looks smart for AstraZeneca, which is worth around $142 billion.

Its stock is trading at a hefty 21 times expected earnings for next year, according to refer native forecasts That gives it a powerful acquisition.