Germany is nationalizing Uniper, its leading importer of Russian natural gas, in an $8 billion deal that underscores Europe's energy crisis

• Germany is nationalizing gas importer Uniper as it seeks to secure its energy supply before winter.
• The government will spend another 8 billion euros on Uniper, having earlier invested 15 billion.

Germany is nationalizing Uniper, its leading importer of Russian natural gas, in a deal that underscores Europe's energy crisis.

Uniper announced Wednesday the German government will acquire a 99% stake in the company, having bought a 30% holding in July as part of a 15 billion euro ($14.9 billion) bailout. The latest deal will involve a capital raise that aims to provide a further 8 billion euros in cash for Uniper, the company said.

Uniper has been struggling since Moscow crimped gas supply to Europe in response to Western sanctions imposed after Russia invaded Ukraine. European natural gas prices have soared 300% this year, with Dutch TTF futures, the continent's benchmark price, up 7.2% to 208.40 euros per megawatt-hour on the ICE exchange early Wednesday.

The supply squeeze and resulting price jump means Uniper has been forced to buy natural gas at higher prices.

"At Uniper, we are aware of our responsibility for Germany and Europe," Uniper CEO Klaus-Dieter Maubach said in a statement Wednesday. "We are committed to doing our part to overcome this crisis and to restructure the energy supply in this country."

The deal announced Wednesday will see Germany buy state-owned Finnish utility Fortum's stake in Uniper for about 500 million euros. Fortum will also be repaid a 4 billion loan to Uniper.

Fortum CEO Markus Rauramo said in a statement: "The role of gas in Europe has fundamentally changed since Russia attacked Ukraine, and so has the outlook for a gas-heavy portfolio. As a result, the business case for an integrated group is no longer viable."

Uniper stock was down 36% to 2.73 euros in Frankfurt, and Fortum stock was up 9.2% to 13.21 euros in Helsinki, at 7 a.m. ET.

Germany's nationalization of Uniper comes as the country attempts to secure its energy supplies before winter. Earlier in September, Germany seized control of three oil refineries owned by Russian energy giant Rosneft. It has also fired up mothballed coal-fueled power plants to help meet demand for electricity.