A number of partners at Grant Thornton Ireland (GTI) are set to depart the firm as it pushes ahead with a $480 million merger with its larger US counterpart, The Currency can reveal. In May, American private equity firm New Mountain Capital acquired a majority stake in the US arm of the professional services giant, Grant Thornton LLP. Five months later it was announced that Grant Thornton LLP would merge with GTI in a deal that included conditions around equity rollovers and performance. Now, seven partners with GTI are primed to exit the business as the amalgamation between the two…