According to Jin10, the Financial Times reported that Mercuria, one of the world’s largest commodity traders, is suing the 282-year-old Baltic Exchange. The British High Court will begin hearing the case on Monday. The dispute centers on whether the exchange should continue publishing benchmark rates for oil tankers transiting the Strait of Hormuz after the U.S.-Israeli war with Iran began this year.

The Baltic Exchange, known in the industry as the “Dow Jones of shipping,” publishes freight rates used by commodity traders to price and hedge derivatives worth tens of billions of dollars. Mercuria argues that shipping traffic through the strait plunged after the war began and Iran declared a blockade, and that the exchange should have suspended its flagship TD3C tanker-route index. Mercuria initially said it had lost “hundreds of millions of dollars,” but later amended its filing, removed its financial-loss claim, and instead sought declaratory relief to have rates published since early March declared invalid.

The Baltic Exchange argues that short-term inactivity on a route is not unusual, ships are still passing through, and it relies on experienced brokers to provide rate assessments. Its lawyers warned that a Mercuria victory could have “chaotic market-wide consequences,” potentially forcing hundreds of trades to be unwound.