Professional services adviser CBIZ has agreed to be taken private by Grant Thornton Advisors in a nearly $3 billion cash deal.

The companies on Wednesday said tax and advisory services provider Grant Thornton will pay $55 a share for CBIZ, a nearly 18% premium to Tuesday's closing price of $46.70 for the Independence, Ohio, company.

The deal, which carries an enterprise value of about $5 billion, would make Grant Thornton the fifth-largest provider of professional services, tax and advisory services in the U.S., with more than $5 billion in annual domestic revenue, the companies said.

Private-equity firm New Mountain Capital, which invested in Grant Thornton in 2024, plans to make a further investment to support the transaction, the companies said, adding that Grant Thornton plans to separate CBIZ's benefits and insurance services segment into a new stand-alone entity backed by New Mountain.

The deal, slated to close by the end of the year, includes a "go-shop" provision that lets CBIZ seek alternative acquisition proposals through Aug. 27, the companies said.