In one of the biggest healthcare mergers of this year, AbbVie has announced plans to buy Allergan, the company behind Botox.

The two pharma giants have entered into a definitive transaction agreement worth approximately $63 billion, based on the closing price of AbbVie's common stock of $78.45 on June 24, 2019.

A primary aim of the merger is to achieve a "diversified product portfolio [that] meets our strategic goal to reduce reliance on Humira", according to AbbVie, as Humira – AbbVie’s blockbuster and also the world’s best-selling drug – gradually loses its patenting around the world, starting in Europe last year.

The companies say that combining Allergan’s diversified on-market product portfolio with AbbVie’s growth platform and expertise in R&D, commercial strength and international footprint will create a leading biopharmaceutical company with approximately $48 billion in combined 2019 revenue, whilst also enhancing AbbVie’s ability for robust investment in its industry-leading pipeline of innovative therapies.

The deal is the second mega merger this year, after January saw Bristol-Myers Squibb put in a $74 billion bid for Celgene.

The acquisition creates “compelling value for Allergan’s stakeholders, including our customers, patients and shareholders. With 2019 annual combined revenue of approximately $48 billion, scale in more than 175 countries, an industry-leading R&D pipeline and robust cash flows, our combined company will have the opportunity to make even bigger contributions to global health than either can alone,” said Brent Saunders, chairman and chief executive officer, Allergan.

He continued, “Our fast-growing therapeutic areas, including our world class medical aesthetics, eye care, CNS and gastrointestinal businesses, will enhance AbbVie’s strong growth platform and create substantial value for shareholders of both companies.”

The deal is expected to close by early 2020.