Quest Diagnostics (DGX) agreed on Wednesday to pay a private equity firm $570 million for Solstas Lab Partners Group, as the testing provider continues to expand its laboratory offerings.

The deal is expected to close in the first half of this year and add about 5% in annualized revenue, Quest said.

The Madison, N.J., company also sees the Solstas acquisition leading to a modest increase in adjusted per-share earnings in 2014.

North Carolina-based Solstas, which is currently owned by Welsh, Carson, Anderson and Stowe, operates in nine Southeast states. Solstas was created when the firm acquired Spectrum Labs in 2010 and then combined it with another company.

Quest, the nation’s largest diagnostic testing company, has turned to acquisitions as it looks to offset lower demand for health services. In October, the company purchased ConVerge Diagnostic Services from Water Street Healthcare Partners.

Shares of Quest increased 18 cents to $54.71 late Wednesday morning.

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