Founded in 1983 and acquired by Companion Life Insurance Company in 2009, iiSi has become one of the leading underwriters of medical stop loss insurance in the country. As a division of Companion Life Insurance Company, iiSi offers the strong combination of stability as a direct writer with the expertise and focus of a managing general underwriter. iiSi’s services include marketing, underwriting, policy and premium administration, and stop loss claim adjudication and payment. In addition to traditional stop loss products, iiSi is also an industry leader in the Reference Based Pricing space. iiSi’s headquarters are in San Francisco, California and has regional marketing offices in Texas and Massachusetts.