InVentiv Health Inc., a provider of services and staffing to the biopharmaceutical industry, announced that private equity firm Advent International acquired a stake and is joining private equity firm Thomas H. Lee Partners as an equal equity owner.

The deal values inVentiv at $3.8 billion, and the transaction is set to close in the fourth quarter. InVentiv has a clinical/scientific staffing division that ranks as the third-largest clinical/scientific staffing provider in the US with 2015 revenue of $150 million, according to Staffing Industry Analysts.

“We’re looking forward to adding Advent’s investment, operational and healthcare sector expertise,” inVentiv Health Chairman and CEO Michael Bell said. “This will allow us to realize our full potential so we can better serve the biopharmaceutical industry in navigating an increasingly complex scientific and regulatory environment.”

As a result of the transaction, inVentiv’s parent company no longer plans an initial public offering at this time.