A Pemex brokered deal for $5 billion in Argentine bonds as compensation to Spain's Repsol for its 51% stake in YPF. The Argentine government nationalized YPF saying Repsol was not investing enough in developing oil and gas reserves. With the discovery of shale gas reserves estimated to be third only to reserves in the U.S. and China and large shale oil reserves, the Argentine government is seeking foreign investment in the oil industry. A settlement with Repsol, with the help of Mexico's Pemex which has a 10% stake in YPF, enables Argentina to seek technology and investment from western oil companies. Chevron has invested in the Vaca Muerta shale field in Argentina.