Health insurer WellPoint has agreed to purchase Amerigroup in a $4.9 billion deal designed to strengthen the company’s Medicaid focus.

WellPoint, based in Indianapolis, will pay $92 per Amerigroup share in cash. When the deal closes, expected in the first quarter of 2013, WellPoint will serve more than 4.5 million beneficiaries of state-sponsored healthcare programs, with a presence in 19 states.