The state holding company Parpública agreed to buy the stake from Pontegadea Inversiones, according to a market filing published by the company on Friday, ECO News reports. REN runs Portugal’s electricity grid and is central to energy security and infrastructure investment.

According to REN, Pontegadea signed a contract with Parpública for the sale of 91,723,676 shares, representing about 13.7 percent of the company’s capital.

The value of the deal was not disclosed, and completion is subject to approval by Portugal’s audit court. Based on REN’s closing share price of 3.54 euros on Friday, before the transaction became public, the stake was worth about 324.7 million euros, Eco News reports.

The transaction marks the Portuguese state’s return to REN 12 years after it sold its last 11 percent stake in 2014.

Montenegro said the state is not seeking to renationalise REN, but to be on the inside of the company to secure Portugal’s strategic interest in its electricity infrastructure, while partaking in strategic investment decisions and helping lower energy prices for consumers and businesses. Montenegro also said the investment fits within the sovereign fund project now being structured by the government.

Pontegadea, the investment holding company of Zara founder Amancio Ortega, had been REN’s second-largest shareholder before the sale, and the largest shareholder remains China’s State Grid, with 25 percent.