Private equity firm Avista Capital Partners and the Ontario Teachers' Pension Plan have agreed to acquire INC Research, a Raleigh company that assists drug makers with clinical trials.

Terms of the deal weren't included in a release announcing the acquisition.

Bloomberg News, quoting an unnamed person with direct knowledge of the deal, is reporting that the two investors are paying about $600 million for INC.

They are buying the privately-held INC from an investor group led by Crosspoint Venture Partners and Adams Street Partners.

“We are enthusiastic to partner with James Ogle, CEO of INC Research, and his talented management team, who have a strong track record of success,” said Neil Petroff, Teachers’ Executive Vice-President and Chief Investment Officer for the pension fund. 

“Under Mr. Ogle’s leadership, we are confident INC Research will continue to capitalize on favorable trends in the clinical development outsourcing market and utilize its global reach to enhance its market share.”