Pohjolan Voima Oy (PVO) is the second biggest Finnish energy company which owns hydropower and thermal power plants (including biofuel-fired power plants). Pohjolan Voima is a founder and main shareholder of the Olkiluoto Nuclear Power Plant operator Teollisuuden Voima Oy. Pohjolan Voima has 25% of shares in the Finnish electricity transmission system operator Fingrid Oyj. Major shareholders of Pohjolan Voima are Finnish pulp and paper manufacturers UPM Oyj (42 0%) and Stora Enso Oyj (15 6).