PRA International’s merger with Pennsylvania clinical research organization ReSearch Pharmaceutical Services is now complete, forming what the combined company says is now the fourth largest CRO in the industry.

Raleigh-based PRA announced the closing of the deal Tuesday morning, nearly two months after announcing the plan to join the two companies to form a larger, global company running clinical trials and providing other services to pharmaceutical companies.

RPS will now operate as PRA’s Strategic Solutions Division. The combined company is led by PRA CEO Colin Shannon. Former RPS CEO Harris Koffer is president of the new division; former RPS President Samir Shah is chief operating officer.

“As a division of PRA, the RPS Strategic Solutions Division will continue to operate as RPS has previously, which should enable a seamless integration with absolutely no disruption for our clients,” Shannon said in a statement.

The merger is the second major transaction for PRA this year. In June private equity firm KKR acquired PRA. No purchase price was disclosed but Bloomberg News, citing an unidentified person familiar with the matter, reported at the time that the price was $1.3 billion. The acquisition followed PRA’s confidential filing of plans for an initial public stock offering.

PRA says that since 2000, the CRO has performed roughly 2,000 clinical trials in more than 80 countries for more than 300 clients. RPS has an established presence in North America and Europe, the Middle East and Africa along with specialized capabilities in Latin America and Asia. The company brings to PRA its 4,000 employees in more than 64 countries. The combined company will have nearly 10,000 employees globally.

Merger and acquisition activity in the CRO sector has been strong in recent years. Mid-size CROs joining forces to gain the global scale needed to compete against the largest CROs for business providing services to pharmaceutical companies around the world. Meanwhile, the biggest CROs such as Durham-based Quintiles (NYSE:Q) – the CRO industry’s largest player – have made more targeted acquisitions of smaller companies that can fill out specialized needs within their organizations.