Insurer UnitedHealth to spend $12.76B on pharmacy benefits manager Catamaran

The nation's largest health insurer, UnitedHealth, is staking a bigger claim in pharmacy benefits management with a plan to buy Catamaran Corp. for more than $12 billion in cash.

UnitedHealth said Monday that it will spend $61.50 on each share of Catamaran in a deal it expects to close during the fourth quarter. That's a 27 percent premium to Catamaran's closing price Friday, and shares of the pharmacy benefits manager, or PBM, are climbing sharply in early morning trading.

Pharmacy benefits managers process claims and run prescription drug plans for insurers, employers and other customers. They help negotiate prices customers and insurers pay for drugs.

UnitedHealth Group Inc. already has a PBM business named OptumRx that fills about 600 million prescriptions annually.

Catamaran expects to fill 400 million this year.