Bloomberg reported that oil speculators are buying options contracts that will only pay out if crude drops to a low of $15 a barrel next year, the latest sign some investors expect an even deeper slump in energy prices.

Bloomberg noted the bearish wagers come as OPEC’s effective scrapping of output limits, Iran’s anticipated return to the market and the resilience of production from countries such as Russia raise the prospect of a prolonged global oil glut.

“We view the oversupply as continuing well into next year,” Jeffrey Currie, head of commodities research at Goldman Sachs Group, wrote in a note, adding there’s a risk oil prices would fall to $20 a barrel to force production shutdowns if mild weather continues to damp demand, Bloomberg said.