Pfizer Inc. said on Tuesday it will buy migraine drug maker Biohaven Pharmaceutical Holding Company Ltd. for about $11.6 billion in cash.

Pfizer will acquire all the outstanding shares of Biohaven not already owned by Pfizer for $148.50 per share in cash, a 78.6% premium to Biohaven's last closing price.

Biohaven shareholders, including Pfizer, will also get 0.5 of a share of a new publicly traded company that will retain Biohaven's non-migraine treatments that are in development stage.

In November, Pfizer acquired overseas marketing rights to two migraine drugs from Biohaven for up to $1.24 billion, with Pfizer taking a 2.6% equity stake in the smaller company.