A huge move for oil could be on tap Monday afternoon, when an unusually high level of activity in September options contracts could set the stage for a vicious rally.

Options on the September crude oil futures contract expire Monday at the 2:30 p.m. ET settlement. And those derivative contracts have been very popular, with many traders using them to bet on more downside for crude.

As of Friday afternoon, more than 23,000 contracts were outstanding on the September 40-strike puts, with several other contracts also seeing elevated positioning.

And this isn’t chump change, either. Each contract controls 1,000 barrels of crude. That means that if oil closes just a dime below $40 at 2:30, the holders of those options will make a collective $2.3 million. Otherwise, they’ll make nothing.

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