On Friday, option traders will face something unprecedented: A monthly options-expiration event coming one day after a holiday when major U.S. stock exchanges will have been closed for business.

Contracts tied to more than $6 trillion in stocks, ETFs and indexes are due to expire during the latest “triple witching” options-expiration event — potentially the largest sum on record, according to data from SpotGamma.

The quarterly undertaking is typically associated with higher trading volumes and greater volatility in the U.S. stock market.

But the June event will take place one day after Thursday’s Juneteenth markets holiday, and a monthly options-expiration event has never before followed a markets holiday, according to Dow Jones data going back to at least 2000 — although there have been numerous examples where monthly expirations occurred on the Friday before a long holiday weekend.

“On the one hand, it has the potential to be a low-volume day; a lot of people will probably take Friday off and make it a long weekend,” said Bret Kenwell, a U.S. investment analyst at eToro, told MarketWatch on Wednesday.

“But triple-witching days are usually one of the most high-volume days of the entire quarter,” he added. “So it does have the potential for maybe some wackier moves, and maybe some bumpiness.”

Adding to the uncertainty, the latest bout of volatility inspired by the Israel-Iran conflict has pushed the Cboe Volatility Index back above 20, a level roughly equivalent to its long-term average. Higher volatility tends to push the premiums that traders pay for option contracts higher. The VIX is based on activity in options tied to the S&P 500.

Brent Kochuba, founder of SpotGamma, said he had initially expected volatility to subside heading into Thursday’s holiday. SpotGamma is a provider of data and analytics about the options market.

“But that may not be in the cards due to the geopolitical backdrop,” Kochuba told MarketWatch via email.

U.S stocks mixed on Wednesday as Federal Reserve Chairman Jerome Powell held his regular press conference following the conclusion of the central bank’s two-day policy meeting.

The S&P 500 fell 1.85 points, or 0.03%, at 5,980. The Dow Jones Industrial Average dropped 44.14 points, or 0.1%, at 42,171. The Nasdaq Composite rose 25.18 points, or 0.13%, at 19,546.