Pharmaceutical giants Pfizer and Allergan are expected to announce a merger as early as Monday that would create the world’s biggest drug company by sales, according to the Wall Street Journal.
The deal would be worth more than $150 billion, and it would be the largest so-called inversion ever. An inversion occurs when a U.S. company merges with a foreign company and reincorporates overseas in order to avoid American corporate taxes. Allergan is based in Dublin, Ireland, and it would take over New York-based Pfizer to locate the merged company outside of the United States. Pfizer CEO Ian Read would lead the company, with Allergan CEO Brent Saunders as the second-in-command, according to the Journal.
The inversion plans come as the United States attempts to block such business deals from moving forward, since they allow companies to avoid U.S. tax obligations. But even new inversion rules by the Treasury Department seem to be unable to stop the Pfizer-Allergan deal, as Fortune reported.
Last year, Pfizer boasted more than $50 billion in revenue; Allergan, which was bought by Actavis, took in more than $13 billion in sales. Their combined portfolio will include Botox, the Prevnar pneumonia vaccine and treatments for ailments including Alzeimer’s and rheumatoid arthritis.
Update: Allergan, when contacted by Fortune, declined to comment. Pfizer also declined to comment.