Equity partners in Grant Thornton ­Ireland could walk away with about €6.5 million in cash each after agreeing to merge their firm with the US group Grant Thornton Advisors for €480 million, according to sources involved in the deal.

The transaction, which is being backed by the private equity firm New Mountain Capital, is believed to feature a 60-40 split between cash and shares in the combined entity, sources close to the negotiations said.

It is understood there are 45 equity partners in the Irish company who will benefit, with another 25 salaried partners who had no vote in the deal and will receive nothing from the New Mountain investment.

The transaction is being done at a ­multiple of 12 times GTI’s earnings of €40