The offer was made through Enel Investment Holding B.V. (EIH), a wholly-owned Dutch subsidiary of Enel SpA, Italy's largest power company. Shareholders have 80 days to respond to the offer, Enel said.
"The tender offer applies to about 22,231 million OGK-5 shares (equal to 62.85% of the Russian company's share capital, net of the 37.15% already owned by EIH] and has been launched at a price of 4.4275 rubles per share, fully payable in cash," Enel said.
In August, EIH received authorization from the Russian antitrust authority (FAS) to increase its stake and buy up 100% of share capital of OGK-5.
Enel, Europe's third largest listed utility by market capitalization, and the second largest in terms of installed capacity, has become the first foreign company to acquire generating assets in Russia in the process of power sector reform.
OGK-5 includes four thermal power plants with total capacity of about 8,700 megawatts, and is one of the most valuable assets spun off from Russian electricity monopoly Unified Energy System, which holds a 50% stake in the company.
The Russian power sector has undergone radical changes in recent years aimed at increasing the efficiency of power plants and developing the industry by attracting investment. During the restructuring process, specialized structures have been created in place of the old vertically integrated companies.
By the end of the reforms, potentially competitive parts of the industry - generation, sales and repair companies - will become mainly private and will compete with each other. However, natural monopoly functions - power transmission and dispatching - will remain state-controlled.