White Mountains Insurance Group will acquire a 51 per cent controlling interest in Distinguished programmes, a US property and casualty insurance programme manager.

The transaction, expected to close in the third quarter, values Distinguished’s equity at roughly $460 million. The Bermudian-based White Mountains will pay $230 million for about half of the outstanding shares, adding to the 1 per cent it already owns. Distinguished will continue to operate under its current leadership team, with private equity firm Aquiline Capital Partners retaining a significant minority stake.

Distinguished manages more than $550 million in premiums across 12 speciality lines, including commercial real estate, hotels, environmental risk, cyber and fine art. The firm does not take insurance risk itself, instead earning commissions from carrier partners.

“Distinguished is well positioned in an attractive and dynamic market,” said Manning Rountree, the chief executive of White Mountains. “We’re excited to partner with a seasoned management team we’ve known for years.”

Jason Rotman, Distinguished’s president, called the deal “a new and exciting chapter” and praised White Mountains’ “deep insurance expertise and outstanding track record”.

Legal advisers for the transaction include Cravath, Swaine and Moore for White Mountains and Willkie Farr and Gallagher for Distinguished and Aquiline. The deal is subject to regulatory approvals.