Oil prices fell more than 2 percent on Thursday, with U.S. crude hitting its lowest level in nearly seven months as last month's steep losses continued into November.
U.S. West Texas Intermediate crude ended Thursday's session down $1.62, or 2.5 percent, at a nearly seven-month low of $63.69. The contract bottomed out at $63.11 earlier in the session, its weakest price since April 9.
Brent crude, the international benchmark for oil prices, was down $2.07, or 2.8 percent, at $72.97 by 2:30 p.m. ET. It fell as low as $72.56 on Thursday.
Both benchmarks posted their worst monthly drop since July 2016 in October, with WTI down nearly 11 percent and Brent tumbling almost 9 percent.
Crude futures got caught up in a broader sell-off in global equity markets in October, sinking as investors sold risk assets. But oil prices have continued to drop even as stocks claw back some gains.
U.S. crude is now trading at levels not seen since the month before President Donald Trump restored sanctions sanctions against Iran, OPEC's third biggest oil producer. The looming sanctions on Iran's energy sector, which go into full force next week, have played a major role in the oil market's rally to nearly four-year highs just one month ago.
Iran's oil exports have shrunk by about a third as crude importers wind down their purchases ahead of Washington's Nov. 4 deadline.
Iran was still selling about 1.7 million to 1.9 million barrels per day in September. The Trump administration is reportedly nearing deals with India and South Korea that would allow the countries to keep buying some of Iranian oil.
The market is also growing confident that output from other sources can offset the declines.
"The Trump administration was saying we're going to go to zero in terms of the amount of exports that Iran was going to be allowed to push out into the market, and in reality the decline in exports from both Iran and Venezuela was more than offset by the increase in exports from other OPEC countries," Micheal Cohen, head of energy research at Barclays told CNBC's "Squawk Box" on Thursday.