Sickness insurance companies were developed in Spain by doctors and healthcare professionals, remaining outside the interests of general insurance companies. Their management was hardly professional, with limited actuarial techniques and they only accounted for a small percentage of total insurance business premiums. From the 1970s onwards, various factors changed this situation, driving processes of concentration, with numerous takeovers and mergers, first reducing the number of local and regional companies to the benefit of companies of national scope. Subsequently, the growth in demand for this type of coverage sparked the interest of national general insurance companies and multinationals, leading to a restructuring of the sector which has progressively acquired greater weight within the insurance business and become increasingly internationalised. This last stage immersed the health sector in Spain in the great processes of globalisation of the sector, characterised by a financialisation of capital promoted by the bank investment funds. These processes are little known and are the focus of analysis of this paper, with the aim of enabling comparison at international level.