Crude oil prices tumbled more than 6% on Monday after OPEC+ surprised markets by announcing a significant increase in production quotas, reversing months of supply cuts that had propped up prices amid weakening global demand.

Brent crude fell to $72.40 per barrel, while West Texas Intermediate dropped to $68.15, marking their lowest levels in over four months. The decision to boost output by 1.5 million barrels per day starting next month caught many traders off guard, as most analysts had expected the cartel to maintain its current production limits.

"This is a clear signal that OPEC+ is prioritizing market share over price support," said Daniel Yergin, vice chairman at S&P Global. "The dynamics within the group have shifted, with several members pushing back against extended cuts that have constrained their revenue potential."

The announcement sent shockwaves through the energy sector, with shares of major oil companies declining sharply. ExxonMobil fell 4.2%, Chevron dropped 3.8%, and Shell lost 3.5% in early trading. Energy-focused ETFs also saw significant outflows as investors reassessed their positions.

The production increase comes at a time when global oil demand growth has been moderating, particularly in China, where economic activity has slowed. The International Energy Agency recently revised its demand growth forecast downward, adding further bearish pressure to the market.