The downward spiral in oil prices is accelerating as a surge in crude production from a turbocharged U.S. petroleum industry runs into weaker global economic growth.

Crude prices slid 7.7% Friday, their largest one-day drop since July 2015, and are now down by nearly a third since the start of October. The U.S. benchmark, West Texas Intermediate futures, closed at $50.42 a barrel—its lowest level in over a year.

As economic growth outside the U.S. has flagged, producers and traders are beginning to worry that demand for crude will also decline. In export-dependent Germany, a purchasing managers index hit a four-year low, well below the level economists were expecting.The steepness of the drop has prompted Saudi Arabia and the Organization of the Petroleum Exporting Countries to consider a plan to quietly cut production to bolster prices, according to people familiar with the matter.

The idea would see the cartel retain the official output targets it set in 2016. But, because Saudi Arabia is overshooting those targets by nearly 1 million barrels a day, it would effectively be a cut. Such a move may help support prices without raising the ire of President Trump, who has been calling on OPEC to keep prices lower.

Investors remain skeptical that the OPEC meeting in Vienna on Dec. 6 will be able to turn the tide on oil supply enough to support prices.