Amgen to buy Otezla for $13.4 billion

Amgen has agreed to buy psoriasis drug Otezla for $13.4 billion in cash, roughly 30% more than Wall Street expected the drug would fetch.

Why it matters: Bristol-Myers needed to sell Otezla, owned by Celgene, to satisfy some federal antitrust concerns over its pending buyout of Celgene. Now the drug giant expects to complete the Celgene deal by the end of this year, but without a growing, lucrative medicine.

By the numbers: Financial analysts expect Otezla will bring in peak sales of $2.5 billion in 2023, when the drug will start to loss broader exclusivity. However, Amgen will hold Otezla's monopoly rights in the U.S. until 2028.

• Amgen also has experience with prolonging drug exclusivity through the courts and patent system.

What to watch: Whether the divestiture wins over the Federal Trade Commission, and whether Amgen will continue Celgene's history of routinely hiking Otezla's price.