The general direction of the development of economic processes greatly depends on the effi­ciency of the development of the public sector. The consequences of the massive privatization of state-owned enterprises, the lack of expected effects of market reforms - these are among the main reasons for the theoretical reflection on the development of the public sector in the Russian Federation. In a context where globalization intensifies, economic and political threats are increasing; there is a real need for a strong and effective public sector, which will provide sup­port to domestic producers, to strategic sectors of the economy, and will become a guarantor of national economic security. The development and implementation of the corporate model of the public sector helps to fulfillment these tasks. But, at the same time they provide an integra­tion effect due to the greater interaction with the private sector. The state sector is represent­ed not only by state unitary enterprises, public joint-stock companies with state participation, but also by the state corporations - these are non-profit organizations, which were created for the implementation of managerial, social and other socially useful functions. State corpora­tions, as a modem institute of economic devel­opment, also play an important role in ensuring the sustainable development of national eco­nomic systems. They neutralize "failures" of the market and create all necessary conditions for overcoming the crisis phenomena. Large state corporations not only contribute to economic development, but also make a significant contri­bution to solving many social issues.

Public sector is the integral element of economy’s structure. On the one hand, the state business promotes accumulation of the capital, provides improvement of branches of economy and strengthens country positions in the world market. From the other hand, the state owns a large part of pro­duction, transport and social infrastructure and it acts as material resources of sustainable development of national economy. In Russian economy public sector takes the essential place either by the volume of the produced and sold products, or by the num­ber of the created jobs. Such companies are among the number of the largest enterprises of public sector as: JSC "OPK" Obo- ronprom ", JSC " Oboronservis ", PJSC" Gazprom ", PJSC" NK "Rossneft", JSC "RZD", OJSC Rostelecom, FSUE "Mail of Rus­sia". These companies function mainly in the defense and social spheres. (Smirnov O.S., 2014).

Natural monopolies, which operate within strategically im­portant sectors of the country's economy and ensure the integrity and security of the social and economic space, are the important tool for state regulation of the economy. The state tries to keep them and, at the same time, to contribute to the development of the competition in those segments where it is possible. (Gogoleva T.N., 2013) Inthe sphere of natural monopolies most of the enter­prises belong to the state, there are even state corporations (such as state corporation “Rosatom”, state corporation “Roskosmos”).

The state sector is a set of enterprises, organizations and in­stitutions which are in the state ownership, at it is managed either by public authorities or the persons employed by them.(Raizberg B.A., 1999) The state sector is considered not only as the sphere of state ownership, the state directly controls its budget and other resources. [Atkinson E., Stiglitz G., 1995] Besides, the economic sector contains economic relations that arise in the production, distribution, exchange, consumption of tangible and intangible goods and services in order to meet public needs and ensure na­tional security.[Podrezova Yu.A., 2008]

The analysis of various interpretations of the concept of "state sector" has shown that its nature is understood in different ways and there are a number of approaches to the definition of the es­sence of the state sector of the Russian economy (Table 1).

According to the institutional approach, the state sector can be regarded as a set of institutions that are heterogeneous in their genesis, such as: unitary enterprises, budget institutions and cor­porations in a broad sense, including non-profit state corporations established on the basis of federal law [Federal Law, 1996] and public joint stock companies with state participation. Such un­derstanding of the public sector allows including a large number of different enterprises and organizations in its structure. This greatly contributes to the expansion of its borders through the coverage of more domestic markets, and the use of forms of co­operation and collaboration.

Flistorically, there is a continuous evolution of the social and economic relations, which is connected with changes in state reg­ulation of economy [Kurchenkov V.V., Fetisova O.V., Chigareva G.V., 2013] and with development of the state sector. The state sector had dominated in domestic economy till 1990. The tran­sition from command and administrative to market economy has significantly influenced the quantitative, qualitative and struc­tural characteristics of the state sector. Unfortunately, results of changes were negative because at that time there were no neces­sary state institutes, financial support and effective mechanisms of realization of reforms. It became obvious that complex justifi­cation and implementation of economic reforms of public sector of Russia is necessary, using the system approach and a clear definition of influence of institutional factors on its development [Mazanova V.V., 2008].

The necessity of the state's participation in economic rela­tions still causes discussions between scientists [Mokina L.S., Nikitina E.G., 2015] and some scientists [Babikova A. V., Hanina A.V., 2015] defend the presence of the state sector in energy, shipbuilding, aircraft and rocketry, railway transport, military-in­dustrial complex and a larger concentration of state-owned enter­prises in strategically important industries of the Russian econ­omy.

We can distinguish three main stages in the evolutionary de­velopment of the state sector of the contemporary Russian econ­omy (Table 2).

At the formation stage, the state sector of the Russian econo­my was functioning due to the state ownership and it had a uni­tary management structure. The state participated as the main agent of economic activity and the main owner. At the stage of transformation, with the formation of a corporate model of the state sector, a part of state ownership was subtracted in favor of state corporations. However, the subtraction was "incomplete", because the state still occupies a dominant position in the sys­tem of strategic management of state corporations, its significant share in the structure of capital of state corporations is still sig­nificant, and in some cases it even dominates (State corporation “Rosatom”, State corporation “Rostechnologii”, State Corpora­tion “Roskosmos”). The transition from the unitary model of the state sector to the corporate model can be defined as the transition from a monocentric model to a polycentric, we mean that homo­geneous structure transforms into a heterogeneous one.

The mentioned stages of the evolution of the state sector of the Russian economy have allowed justifying the genesis of opportunities and to use alternative models of development of the state sector of the Russian economy (unitary, corporative, mixed). Thus, the unitary model of the state sector is represented by state unitary enterprises, which are in full state ownership. Large state corporations and public joint-stock companies with state participation form the corporate model. The mixed model combines features both of unitary and corporate models. It has either corporate structure with a share of state capital, or state- owned enterprises which main resources are owned by the state.

The development of corporate relations has had a significant impact on the patterns of formation of the structure of the state sec­tor. The general dynamics of the development of the state sector in quantitative terms is characterized by several trends. There is a formal reduction of number of the unitary state enterprises, and the integration of the state assets into the large holding companies and state corporations continues. The enterprises are restructured in such way that large corporate associations are formed, most of whose shares belongs to the state, including the fact that vertically integrated structures appear. The increase in a share of the state in private corporations, the creation of large corporate structures with the state participation allow us to talk about formation of new model of public sector of the Russian economy. Successful state corporations operate in key sectors of the national industry; and they make a significant contribution to the development of international economic relations of Russia [Smirnova O.S., 2013]. Under the current circumstances, the question arises: what is the optimal model of the state sector of the Russian economy? The main features of the corporate model of the state sector are reflect­ed in Table. 3

In a situation where globalization continues, the activities of foreign multinational companies are suppressing the Russian economy, that is why it is necessary to increase the competitive potential of the national economy. A corporate model of the state sector of the Russian economy, with the participation of large state corporations, which are capable of creating competition with foreign multinational companies, should be developed [Kalmykova T.N., 2013].

To our mind, the following principles should make the basis for the corporative model:

The analysis of peculiarities of fonnation and realization of cor­porate model of public sector of the Russian economy has allowed revealing its advantages and shortcomings (Table 4).

Achievement of integration effect is the main advantage of corporate model of public sector of the Russian economy. Inte­gration potential of basic elements within the public sector rises, particularly, the unitary enterprises, scientific and educational institutions, etc. are increasing. Interaction borders with the private sector extend due to the opportunities of joint possession of the share capital at implementation of joint projects within public-private partnership, diversifications of a portfolio of the state order, expansion of commercial functions of new subjects of public sector. New possibilities for the relative growth of the sizes of state sector and the actual expansion of its borders due to strengthening of transitional elements, due to the development of corporate and associative forms of integration with the enterpris­es of the private sector are created. If we compare, the classical or unitary model of state sector promotes isolationism and disinte­gration either the internal elements which are its part, or external elements, including the enterprises of the private sector.

This model assumes increase in the sizes of state sector, namely, the number of the state unitary enterprises, which is rath­er problematic in modem conditions. In this regard, the potential of growth of the sizes of state sector within classical unitary mod­el is very limited.

The state corporations which have formed three main groups were created in 2007:

The state corporations function in priority branches and per­form a number of important functions in the public sector’s struc­ture. Among them we can name:

For assessment of key performance indicators of the state corporations it is important to modify the existing system of assessment of their efficiency in such way, that it should in­clude basic criteria, which reflect internal efficiency of the cor­poration as economic subject or economic unit. It also should include derivate, which reflects the external economic, social and environmental effects of the entire public sector, industry and the economy as a whole. The improvement of its strategic planning system is an important direction in increasing the efficiency of the institute of state corporations. It is directed to optimize structural elements of basic strategy and to achieve the state corporation, which is complementary to type of the chosen reference strategy (the concentrated growth, vertical integration or diversification strategies).

The peculiarity of choosing some definite strategy of a state corporation depends on its type. Conditionally, state cor­porations can be divided into several groups (table 5) depend­ing on a combination of features reflecting the degree of state participation in the assets, and level orientation of production and economic activities to a competitive market, market trans­actions. [Kyrchenkov, V.V., Kalmukova T.N., 2013].

According to the theory of O.V.Inshakova about distinction the institutional status of the enterprise and firm [Inshakov O.V., 2018], we should mention that only state corporation, which are included in the sector A-D will have a greater degree of institu­tional features of the companies. At the same time, the state cor­porations, which belong to the sector B-C, they will have features of the classical enterprise of a centralized planned economy. That is why, in modem conditions institutional borders of the state cor­porations are rather unclear, because structures of this type are extremely various, and they differ by the sizes, structure, sector affiliation.

Optimization of structure of state corporation strategy is connected with the necessity to allocate such obligatory ele­ments as: "definition of a mission and purposes", "analysis of external and internal environment", "development of the pro­gram of actions", "statement of target indicators and resource ensuring realization of strategy". Besides, the type of the organ­izational and functional configuration of state corporation has to correspond to the type of the chosen strategy (table 6). For such state corporations as “Vneschekonombank”, “Agenstvo po strahovaniy vkladov”, “Fond sodeistviia reformirovaniy GKH” the type of strategy of the concentrated growth, connected with strengthening of positions in the market, is peculiar. State corpo­rations as “Rosteknologii”, “Rosatom” and Roskosmos” chose the strategy of diversified growth, which is connected with the diversification of the product portfolio and the emergence of new, fast-growing markets. Implementation of the chosen strate­gy will allow the state corporations to develop effectively in the long term perspective and to successfully carry out their goals, including those, connected with support of strategic branches of the Russian economy.

Advantages of the corporate model of state sector are caused by the advantages of large corporations, which are connected with unlimited development opportunities and diversification of production, with receiving of high profit and with the introduc­tion of new technologies. The state corporations activity is car­ried out in perspective sectors of national economy, the effective development of which depends on the successful development of the country's economy as a whole. The state corporations help smoothing of "failures" of the market by creating all necessary prerequisites for the elimination of consequences of the crisis phenomena by providing sustainable development of national economic system. Within public sector the state corporations perform a number of important functions, first of all reproduc­tion, innovative and stabilization function and also ensure nation­al security. Consolidation of the state capital in the large state corporations allows developing in a complex and effective way some strategic branches of economy. Successful formation and development of corporate model of public sector of the Russian economy directly depend on efficiency of functioning of the state corporations, which make a basis for formation of this model. Development of the state sector promotes consolidation of the state capital in strategically important branches of economy by means of merging of economic entities in the large state corpo­rations. This allows to provide high diversification of production and considerable scales of activity and effective implementation of separate types of state policy.