Mexico revealed on Thursday it had built a massive position in oil “put” options, a financial instrument that gives holders the right to sell at a predetermined price and date, in an effort to lock in its oil revenues for next year.

Agustín Carstens, the country’s finance minister, said Mexico bought 330m barrels worth of put options for 2009, securing a minimum price of $70 for the country’s crude oil export mix, which roughly translates to $85 for the West Texas Intermediate benchmark. “It is an immense program,” Mr Carstens said.