White Mountains Insurance Group, Ltd. is an insurance holding company. The Company's principal businesses are conducted through its insurance, reinsurance and insurance services subsidiaries and affiliates. Its segments include OneBeacon, Sirius Group, HG Global/BAM and Other Operations. The OneBeacon segment consists of OneBeacon Insurance Group, Ltd., a limited liability company that owns a family of property and casualty insurance companies. The Sirius Group segment provides reinsurance and insurance products around the world for property, accident and health, aviation and space, trade credit, marine, agriculture, and certain other exposures through its subsidiary, Sirius International. The HG Global/ BAM segment is a mutual bond insurance company. The other operations segment consists of the Company and its intermediate holding companies.