Kendle International Inc. (Nasdaq: KNDL) shares rose 57.8% Thursday to $14.99, a day after INC Research LLC said it would acquire the clinical research group for $232 million, or $15.25 a share. Volume for the stock was 3.2 million in the just the first hour of trading, compared to an all-day average around 158,000.

The purchase price represents a 60.5% premium over Kendle’s closing share price on May 4, and a 51.3% premium over the 30-trading day average of Kendle’s closing price. Kendle’s Board of Directors of unanimously approved the transaction, which is expected to close in the third quarter.

Kendle CEO Stephen Cutler commented, “Joining forces with INC Research is the right decision for our customers and shareholders. Combining our highly complementary assets will provide the scale and scope for the combined company to deliver outstanding global teams, therapeutic expertise and operational excellence for clinical trials of all sizes.”

Concurred INC CEO James Ogle, “The combination of INC Research and Kendle will enable us to deliver broader capabilities and reach a critical mass for the emerging drug development outsourcing and alliance partnership models. Together, we bring complementary strengths and expand the breadth and depth of services and expertise that are most valuable to our customers.”

INC based in Raleigh, North Carolina, is a therapeutically focused global contract research organization (CRO) privately held by Avista Capital Partners and Ontario Teachers’ Pension Plan.

Kendle International, headquartered in Cincinnati, is a leading global clinical research organization providing the full range of early- to late-stage clinical development services for the world’s biopharmaceutical industry.