Mexico does it, Russia probably wishes it had, oil companies almost never do. Perhaps they should? Agustín Carstens, Mexico’s finance minister, crowed like a rooster when he revealed last week that the country had hedged a full year of oil exports, some 300m barrels. The price of Mexico’s crude may have plummeted to $45 a barrel. But Carstens’ punt, perhaps the largest of its kind, secured Mexico a minimum price of $70, profiting the country $10bn at current oil prices.

Oil majors rarely hedge, rightly believing investors prefer unhedged exposure. Still, any company that forward-sold oil two months ago would have locked in prices twice today’s. The only exception to this general corporate rule is deals. If a takeover makes economic sense at a current oil price, but not if the price falls, one solution is to hedge. The trouble is if prices rise. Hedging losses can then cause the chief financial officer to fall on his sword.