KKR & Co. LP said on Wednesday it had agreed to acquire ReSearch Pharmaceutical Services Inc (RPS) from private-equity peer Warburg Pincus LLC, marking its second announced investment in a global contract research organization in as many months.

Terms of the deal were not disclosed, but a person familiar with the matter said RPS had earnings before interest, tax, depreciation and amortization of about $30 million.

In June, KKR said it was buying clinical research group PRA International from Genstar Capital LLC for an undisclosed amount, but a source familiar with the matter said the agreed price was around $1.3 billion.

Upon closing both deals, KKR plans to merge PRA and RPS, with PRA Chief Executive Officer Colin Shannon leading the combined company, according to a press release issued by KKR. The deal is expected to close in the third quarter.

Warburg Pincus took RPS private in 2011 for $227.3 million. The Fort Washington, Pennsylvania-based clinical trials company has more than 5,000 employees and operations in more than 64 countries, according to its website.

Citigroup and law firm Kirkland & Ellis LLP advised RPS. Credit Suisse, Jefferies LLC and UBS Investment Bank served as financial advisers to KKR. Simpson Thacher & Bartlett served as legal counsel for KKR.