Pharmaceutical companies Pfizer Inc. and Allergan PLC have decided to combine to form a global drug behemoth. The $160 billion tax-inversion merger would be the largest deal ever sealed in the pharmaceutical world. The transaction is expected to be completed in the second half of 2016. Under the terms of the deal, all Pfizer shareholders will receive one stock of the combined company for each of their shares while Allergan shareholders will get 11.3 shares for every stock they currently hold. The combination of Pfizer and Allergan will create the world’s biggest pharmaceutical company, with joint annual sales of more than $60 billion. Experts say this deal is expected to be neutral to Pfizer’s adjusted earnings per share in 2007, which would presumably start adding up no sooner than in 2018. The parties estimate that their merger would boost the corporation’s profits by 10 percent by 2019. Following the news, shares of the New York-based Pfizer dropped by 1.7% while shares of Allergan, headquartered in Dublin, posted a 2.9-percent decline. By the end of the past week, Allergan’s market cap exceeded $120 billion, and the total capitalized market value of Pfizer was almost $200 billion. Therefore, the combined stock market capitalization of the new pharmaceutical giant is likely to go beyond $300 billion. The present Pfizer-Allergan mega-merger is the biggest deal ever signed in the pharmaceutical sector, surpassing another record-making acquisition made by Pfizer. In 2000, the company acquired Warner-Lambert Co. for $116 billion.