Founded in 1980, White Mountains Insurance Group, Ltd. is a publicly-traded financial services holding company (NYSE: WTM). The company's business model is centered on a disciplined, long-term, "buy-to-build" strategy, acquiring and growing businesses in the insurance, reinsurance, and financial services sectors. Their primary operations include specialty property and casualty insurance and reinsurance through subsidiaries like Ark Insurance Holdings and NSM Insurance Group.