AbbVie sent shockwaves through the drug industry, announcing that it had reached a deal to acquire Allergan for approximately $63 billion.

The deal will bring Allergan and its blockbuster Botox under AbbVie’s roof, giving AbbVie some security as the exclusivity for rheumatoid arthritis blockbuster Humira nears its expiration, in 2023. Humira earned global sales of almost $20 billion in 2018, while Botox earned $3.6 billion.

The merger will relocate Allergan’s headquarters from Dublin, Ireland to AbbVie’s realm in the Chicago suburbs. The deal is subject to federal review, but it’s roughly half of what was on offer three years ago, when Pfizer walked away from a proposed $160 billion takeover of Allergan.