The aim of the article is to disclose a systematic approach to the formation of mandatory accumulative pension provision on the basis of the object-subject approach in the coordinates of «effectiveness – risks». The system of mandatory accumulative pension provision is proposed to be considered as an aggregate of interrelated elements, in particular, such as: objects, subjects, tasks, principles, sources of financing and other components that ensure effectiveness and focus on achieving social and economic effect, taking into account the existing risks of external and internal nature. The main objective of such a system is specified, which is to accumulate a sufficient amount of pension contributions to ensure appropriate pension payments, taking into account the need to form investment income adjusted for the inflationary component, existing risks and restrictions on the placement of pension assets. It is noted that the accumulative mandatory pension provision in the conditions of wartime and post-war recovery of Ukraine should be considered as an element of the transformation of the pension system. The social effect is achieved in the form of accumulation of a supplement to the basic old-age pension for pensioners, which reflects the receipt of pension payments both immediately and in installments under the agreement and depends on the diversification of investments in cash on deposit pension accounts, assets in securities and other assets not prohibited by current legislation. It is expedient to consider the economic effect as a source of financing economic transformations through stock market instruments that activate the mobilization of financial resources for investment in various sectors of the economy. It is proposed to identify specific risks of accumulative pension provision, which include: operational, investment, risks of unbalanced liquidity; environmental, social and governance risks associated with the pension portfolio and its management, interest rate risk. Further research will be aimed at developing a conception for the development of pension provision in Ukraine in the post-war period, taking into account the legal, financial and organizational foundations for the introduction of mandatory accumulative pension provision.