(Image source from: Largest ever deal in healthcare of over $150 billion set by Pfizer})

On Sunday, a formal board approval came from Pfizer to acquire Botox maker Allergan in a deal more than $150 billion, which is largest ever in the healthcare sector.

The deal that would be announced on Monday would definitely draw political ire in a U.S. presidential election year. This because of the possible redomicilation of Pfizer to Ireland, as Allergan is registered there. This comes as a so-called "inversion", to slash corporate tax rate.

As per the deal, Pfizer would pay with 11.3 of its shares for each Allergan share. There would also be a small cash component that accounts for less than 10% of the deal’s value, according to sources.

Ian Read, 62, is the current Chief Executive of Pfizer and will be the CEO of the combined company. Brent Saunders, 45, Allergan's CEO will focus on operations and the integration. Sources also revealed that Saunders be a member in the combined company's board. Pfizer and Allergan have declined to comment on the deal.

On Friday, Pfizer shares closed little changed at $32.18, while that of Allergan's rose 3.4 %to $312.46, both on the New York Stock Exchange.

-Sumana