Repsol YPF, the owner of 25% of the Carioca oil field offshore Brazil, had a record gain in Madrid trading after the Brazilian authorities said the field is probably the largest oil discovery in the last three decades, and the third-largest ever drilled.

Repsol rose as much as 3.25 euros, or 14 percent, to 26.75euros, the biggest increase since the company sold shares to the public in January 1990. It closed the day at 25.68 euros, a 9.277% increase that erases all Repsol’s stock losses for 2008.

Petrobras, the Brazilian oil giant who owns 45% of the project, said yesterday that more investments are required to drill new wells, and conclusive data on the discovery’s potential will only be known after the other phases involved in the assessment process have been completed. Petrobras shares soared more than 8% in yesterday’s New York trading.

The remaining 30 percent of the project, is hold by BG Group Plc, the U.K.’s third-largest natural-gas producer, BG shares gained as much as 103 pence, or 8.4 percent, to record 1,325 pence in London trading. It closed 5.810 up to 1293 pence.