OPEC‘s limited impact on oil prices since securing a landmark deal to curb oversupply shows its dwindling influence in the energy market, according to the head of commodities research at Commerzbank.

“The fairly short-lived effect of production cuts on oil prices shows that OPEC’s market impact via ‘supply control’ is very limited. We have been pointing out for years that OPEC has lost its ‘pricing power’,” Eugen Weinberg, head of commodities research at Commerzbank, said in a note.

“Even so, OPEC is unlikely to throw in the towel already and make another U-turn, but will extend the agreement instead,” Weinberg added.

The Organization of the Petroleum Exporting Countries (OPEC) and other producers, including Russia, agreed to slash output by almost 1.8 million barrels per day in the first half of the year. The historic deal was struck in an attempt to remove a supply overhang which has depressed prices to less than half their 2014 highs.