Professional employer organization Oasis Outsourcing, one of the largest PEOs in the US, announced private equity firm Kelso & Company purchased a “significant” interest in the company. The terms of the transaction were not disclosed.

Stone Point Capital, which acquired the PEO in 2014, remains the majority owner of the company, with the remainder owned by Oasis management.

“I am delighted to add Kelso to our team,” Oasis President and CEO Mark Perlberg said. “Being backed by two outstanding private equity partners will further enable us to continue to invest in our business, both organically and via strategic acquisitions.”

Oasis Outsourcing most recent acquisition was last month’s deal for DHR Services Holdings LLC and its subsidiaries, which expanded its geographic footprint in the Western region of the US. Both firms serve clients in numerous industries including hospitality, technology, engineering, education, property management and more. Oasis now counts more than 7,500 clients and 230,000 worksite employees nationwide.