Oil prices slipped below the psychologically important level of $40 a barrel during trading Monday, and another $5 drop could be on the horizon, according to analysts.
Bets that U.S. crude's West Texas Intermediate contract will rise have "pretty much evaporated" as the assumptions underpinning the bull case for oil have collapsed, Again Capital founding partner John Kilduff told CNBC.
A Reuters survey released Friday showed OPEC output likely hit the highest level in recent history. On the same day, oilfield services firm Baker Hughes reported drillers increased the number of rigs operating in U.S. fields for a fifth straight week.
Meanwhile, Saudi Aramco reduced the official selling price of benchmark Arab light grade, sparking fears of a renewed battle for market share among OPEC members that could put more crude into an already oversupplied market.
Oil watchers had already feared another leg lower as refined-products stockpiles hit record levels, reducing demand for crude just as peak driving season in the United States comes to a close and refiners prepare to shut facilities for fall maintenance.
"There was a thought the strong gasoline demand would drain the swamp but it hasn't," Kilduff said, adding that "I think we're going to ultimately head down to at least $35."
Traders last week told CNBC that a fall below $40 a barrel opens the possibility of a move toward $36. At that level, Kilduff said traders would have to reconsider whether oil prices could test last winter's low of $26.05 a barrel.
Mike Dragosits, senior commodities strategist TD Securities, also identified $35 as a critical support level.
However, he said WTI's break below its 200-day moving average on Monday occurred on normal volume, potentially signaling that the decline is a "fake-out push." He said stronger volume would be a signal of more downside.
Still, he doesn't think a $20-handle is in the cards for oil.
"I think if it got down to $35, you'd have people stepping in. The fundamentals are a lot better than they were at the beginning of the year," Dragosits told CNBC.
WTI dipped below its 200-day moving average of $40.76 last week, but futures at that time bounced off the move to close slightly higher on Friday.
Tamar Essner, energy director at Nasdaq Advisory Services, told CNBC's "Squawk on the Street" on Monday that she believes oil can trade below $39 intraday, but does not believe crude will languish at $40 a barrel on a sustained basis. She noted that while short positions have indeed risen to near February levels, investors have not cut their long positions as deeply as they did at that time.
— CNBC's Patti Domm contributed to this story.