Mubadala Investment Co. is planning to divest 25% of its ownership in Spanish oil and gas company Cepsa in an initial public offering (ipo).

The offering, which is set to take place in the fourth quarter of 2018 subject to market conditions, could fetch about €3 billion, valuing Cepsa at €10 billion and potentially making it the biggest oil ipo in the past decade.

Quoting people familiar with the matter, Bloomberg news agency said that the Abu Dhabi holding company decided on an ipo rather than a sale after potential bidders for Cepsa were narrowed down to private equity firm Carlyle Group.

“We are committed to delivering the ipo with a listing on the Spanish Exchanges as a natural and strategic fit for Cepsa that will provide wider access to capital markets to support financial flexibility,” said Musabbeh Al Kaabi, CEO for petroleum and petrochemicals at Mubadala.

The ipo will be listed on four Spanish exchanges – Madrid, Barcelona, Bilbao and Valencia.

Mubadala’s predecessor International Petroleum Investment Co. took control of Cepsa in 2011. Mubadala also owns Canada’s Nova Chemicals and holds a 64% stake in major polyolefins producer Borealis.