White Mountains Insurance Group, Ltd., through its subsidiaries, engages in the property and casualty insurance, and reinsurance businesses. It operates in three segments: OneBeacon, Sirius Group, and Other Operations. The OneBeacon segment offers professional liability, marine, collector cars and boats, property and inland marine, tuition reimbursement, and excess property and accident and health insurance products, as well as property and casualty insurance coverages tailored to industry groups, such as technology, financial services, entertainment, sports and leisure industries, and government entities. This segment provides a range of insurance products through independent agencies, regional and national brokers, wholesalers, and managing general agencies. The Sirius Group segment offers insurance and reinsurance products for property, accident and health, aviation and space, trade credit, marine, casualty, agriculture, contingency, and other exposures. This segment also specializes in the acquisition and management of run-off insurance and reinsurance companies. The Other Operations segment provides investment management services to third parties; and reinsures death and living benefit guarantees associated with variable annuities issued in Japan. The company offers its products and services primarily in the United States, Europe, Canada, the Caribbean, Bermuda, Latin America, and Asia. White Mountains Insurance Group, Ltd. was founded in 1980 and is headquartered in Hamilton, Bermuda.