Sirius International Insurance Group has acquired the runoff loss reserve portfolio of Bermuda-based reinsurer Old Lyme Insurance Company.

The companies have signed novation agreements through which Old Lyme loss reserves of $23m were transferred into a Bermuda reinsurance subsidiary of Sirius Group.

The transaction was led by White Mountains Solutions, the specialist runoff acquisition team of Sirius Group.

White Mountains Solutions president Neal Wasserman said that this was a somewhat unusual transaction structure for the runoff sector – and represents an example of their flexibility in working with clients to find creative solutions for bringing closure to their legacy liabilities.

White Mountains Solutions said that Old Lyme is the seventh runoff acquisition it has completed.

Sirius International Insurance Group is a wholly owned subsidiary of White Mountains Insurance Group, a Bermuda-based financial services holding company.