Pharmaceutical giant Pfizer Inc (NYSE:PFE) secured board approval over the weekend for the acquisition of rival company Allergan Plc (NYSE:AGN) in a deal that will create the world’s biggest drug company, Reuters reported this morning.

Its sources stated that the merger will be worth more than $150 billion – the largest deal this year, including that of SABMiller – and would involve Pfizer paying with 11.3 of its shares for each Allergan share. The companies’ boards of directors reportedly approved the deal Sunday, but Reuters’ sources have said that final details will be released later today.

A major bonus of the merger is that Pfizer will be able to redomicile to Ireland, where Allergan is based, and slash its corporate tax rate from the 35 percent it pays in the US to the Irish rate of just 12.5 percent.

The deal would put the merged group well above the competition, with combined annual sales of $60 billion. Pfizer and Allergan declined to comment.

Pfizer is currently trading down 0.34 percent, with Allergan up 3.57 percent on the news. (0837GMT)