Crude prices fell on Monday in the first trading session after OPEC members failed to agree on output targets to reduce a bulging oil glut that has cut prices by more than 60 percent since June 2014.
The Organization of the Petroleum Exporting Countries failed to agree on an oil production ceiling meant that the group for the first time in decades didn't even mention an output quota, which previously stood at 30 million barrels per day (bpd), Reuters reported.
"Past communiques have at least included statements to adhere or maintain output in line with the production target (of 30 million barrels per day). This one glaringly did not," Barclays bank said.
By ditching any output limits, analysts said the group was sending a message to other producers such as Russia or North American shale drillers that it was willing to accept low oil prices to defend market share.
"OPEC is sending an ultimatum to its competitors: the fall in oil production should come from them," OCBC bank said.
Morgan Stanley said OPEC "believes its strategy is slowly working".
OPEC's output of more than 30 million bpd has compounded an oil glut, pushing production 0.5 million to two million bpd beyond demand and putting many producers under pressure, especially small-sized US shale drillers which have piled up large amounts of debt.
US crude was trading at $39.52 a barrel at 0414 GMT on Monday, down 45 cents. Internationally traded Brent futures were down 35 cents at $42.66 per barrel. This left both benchmarks near 2015 lows and not far off levels seen during the peak of the global financial crisis of 2008/2009.
"The effective removal of the OPEC quota leaves the market in a more vulnerable position. Prices are likely to weaken this week as the market turns its attention back on US supply," ANZ bank said, referring to near record US crude inventories of almost 490 million barrels.
"With Iran exports likely to start increasing next year, this increases the likelihood of further weakness in crude oil markets," ANZ bank said.