"Apparently Saudi Arabia is now concentrating more on defending its market shares on the US market, which could pose a problem in particular for Canada, Mexico and Venezuela (other leading suppliers of oil to the US) and for US shale oil producers," said Commerzbank on Tuesday. "With just three-and-a-half weeks to go before Opec’s meeting, however, Saudi Arabia does not appear willing to curb its supply. This makes it rather unlikely that any agreement to jointly reduce production will be reached on November 27 and suggests that pressure on oil prices will persist."