White Mountains Insurance Group Ltd announced it has agreed to acquire a majority equity stake in NSM Insurance Group.

NSM is a specialty insurance programme administrator and the deal values the company at about $388 million.

Bermudian-based insurance group White Mountains intends to fund the acquisition through a combination of cash on hand and new debt issued by NSM.

NSM places in excess of $500 million in premiums annually through its relationships with more than 6,000 brokerage firms and approximately 100 insurance carriers. NSM’s expertise covers a wide range of specialty insurance sectors such as collector cars, non-profit organisations, sports and wellness centres, specialty real estate and pet insurance.

In a statement, White Mountains said NSM’s “deep industry knowledge and capabilities and longstanding relationships with insurance brokers and insurance carriers allow it to serve as a critical intermediary in the specialty insurance market”.

Manning Rountree, chief executive officer of White Mountains, said: “We are pleased to make this investment in NSM alongside the management team.

“The company is high quality, and we believe there is tremendous opportunity to grow and expand the business. We look forward to working with Geof and his team and to providing them with support and resources to continue to grow the business organically and through acquisitions.”

Geof McKernan, CEO of NSM, said: “This transaction marks a new and exciting chapter of growth for NSM. We are thrilled to have the support of an experienced insurance investor with a long-term capital base as we set our course towards future success.”

The transaction is expected to close by the end of the second quarter of 2018. The closing is subject to regulatory approvals and other customary closing conditions. The closing is not subject to a financing condition.