(Bloomberg) -- Investors have ramped up wagers in a relatively obscure corner of the oil market that OPEC+ output hikes will lead to an eventual glut toward the end of this year and into 2026.

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Open interest in calendar spread options — the difference between West Texas Intermediate crude’s value over different delivery months — this week reached a record high, according to CME Group. The Commodity Futures Trading Commission’s latest report shows that speculators hold the biggest net position wagering on a weaker US crude futures curve since 2020.

Oil traders are grappling with a host of major market drivers, from President Donald Trump’s tariff war against some of the US’s largest trade partners to an OPEC+ decision to add more barrels back to the market than was previously expected. On the flip side, there are also persistent geopolitical concerns looming over output from Russia to Iran and Venezuela.

Those headline risks have made taking relatively cheap wagers on the structure of the forward curve more attractive, particularly with a glut expected to emerge later this year. At the same time, though, in the here and now markets remain robust, meaning not all of the flows have been betting on lower prices. It reflects the unusual “hockey-stick” shape of the curve, where the market appears to be pricing tight supply through the end of 2025, then an oversupply next year.

“There is a lot of risk in the trade,” said Nicky Ferguson, head of analytics at Energy Aspects Ltd. Rising activity has been driven by “strong prompt, weak deferred balances, and a very changeable geopolitical environment that makes holding futures difficult.”

The WTI July-August spread weakened 3 cents Thursday to $0.93 a barrel as of 10:21 a.m. New York time, while December 2025-December 2026 was 10 cents stronger at $0.53.

Some of the biggest bets would benefit from a collapse in the curve at the end of this year. Against that, in recent days buying of nearby contracts that would profit from a spread of more than $1 have helped propel the US benchmark’s prompt timespread higher.

The large positions could accelerate sudden moves in the intermonth spreads if dealers who have sold options need to re-balance their books by buying into rallies or selling into declines.