MercoPress. South Atlantic News Agency

Rockhopper and Navitas shares fall as operators defend Sea Lion timetable

”The partnership operates pursuant to valid petroleum licences lawfully granted to it by the government of the Falkland Islands, a self-governing UK Overseas Territory

Shares in the two companies developing the Sea Lion field off the Falklands fell on Friday after Argentine President Javier Milei announced he would tighten sanctions on firms operating around the archipelago without authorization from Buenos Aires. Both companies responded with a joint statement saying they do not anticipate any impact on the project's development.

Stock in Britain's Rockhopper Exploration dropped more than 10% on the London Stock Exchange, to 69 pence, in early trading, before trimming losses to around 72.9 pence, some 6.5% below the previous close. Shares in Israel's Navitas Petroleum, the project's operator, fell about 2.3% on the Tel Aviv exchange.

“The partnership operates pursuant to valid petroleum licences lawfully granted to it by the government of the Falkland Islands, a self-governing UK Overseas Territory, and with the full and ongoing support of the UK Government,” the companies said. They added that recent developments are not expected to have a material effect on development activities or on the project's timetable. Rockhopper issued the text as a notice to London's Regulatory News Service, titled “Sea Lion Operator Update following Media Reports.”

In his address on Thursday night, Milei said the project “has a date to begin offshore oil production sometime in the coming months” and announced a decree to speed up sanctions and bar those companies, their shareholders, directors and suppliers from operating on Argentine soil. The consortium's official schedule places drilling in early 2027 and first oil in 2028.

Navitas holds 65% of the project and Rockhopper 35%. The two took the final investment decision in December 2025, worth $1.8 billion, for the first phase of the development, located some 220 kilometers north of the archipelago in the North Falkland Basin, in 450 meters of water. Reserves are estimated at 1.7 billion barrels. In August, Navitas exercised a $125 million purchase option on the vessel OSX-1, which will serve as a second floating production, storage and offloading unit alongside the Aoka Mizu.

The reaction was not confined to the Sea Lion partners. Borders & Southern Petroleum, listed on London's AIM market and holder of a 100% interest in three production licenses in the South Falkland Basin around the Darwin discovery, also fell despite having no stake in the field.

The announced measures extend a regime already in place. Resolution 133/2012 of Argentina's Energy Secretariat declared Rockhopper's activity clandestine, and in December 2025 the Foreign Ministry formally warned individuals, companies, financial institutions, suppliers and insurers about the consequences of taking part in unauthorized operations. This week, environmental lawyers and 1982 war veterans also filed a lawsuit in Argentina challenging the legality of the permits and the potential environmental impact of the project.