Grant Thornton set for $5bn CBIZ buyout in landmark accountancy dealGrant Thornton Photo by J. David Ake/Getty ImagesGrant Thornton is set to buy New York-listed management consulting firm CBIZ in a proposed $5bn deal, one of the largest transactions of its kind in the accountancy sector, creating the fifth-largest professional services firm in the US. CBIZ, the only audit firm listed on the US stock market, is set to be acquired by Grant Thornton Advisors’ backers, private equity firm New Mountain Capital, after a year of record-low share price. Private equity dominates the industryThis deal comes as its UK arm became the largest UK professional services business to accept external equity investment after agreeing to be acquired by private equity firm Cinven. On Tuesday, it was revealed that Grant Thornton’s UK equity partners received a £35.2m payout after the large external stake. City-based Blick Rothenberg is widely recognised as the first major UK accountancy firm to receive private equity backing, following HgCapital’s investment in July 2016.