A magnitude-9 earthquake and tsunami led to a meltdown at the Fukushima nuclear power plant in Japan. German Chancellor Angela Merkel, in response to the nuclear disaster, ordered eight of the country's 17 nuclear reactors closed by year's end and a total shutdown by 2022.
Sebastian Kauffmann, a utilities analyst at German brokerage company CA Cheuvreux, said Merkel's decision might cost RWE about $551 million in earnings and E.ON around $820 million.
"The nuclear exit caught both off guard," he told the Financial Times.
Sofia Savvantidou, an analyst at Citibank in London, said it appears E.ON was already looking for opportunities outside the eurozone, noting RWE wasn't as prepared.
Yet RWE, though still waiting for approval, is said to be in talks to form a joint venture with Russian energy company Gazprom, one of the biggest energy companies in the world.
RWE in May said it was teaming with Russian research organizations Kurchatov Institute and Skolkovo Foundation to explore "pro-climate energy generation and utilization." E.ON and Gazprom, meanwhile, are part of the consortium overseeing the Nord Stream natural gas pipeline to Germany.