Brexit’s $74 Trillion Battle Over Derivatives Is Heating Up

London’s dominance of the derivatives market is under threat, with European firms at risk of being blocked from using clearinghouses in the British capital within six months.

Industry groups fear that contingency measures already accepted by Brussels officials to grant access until the end of March 2020 don’t defuse the threat posed if the political storm in Westminster pushes the U.K. out of the bloc without a deal on Oct. 31. At risk are derivatives contracts with a notional value of as much as 60 trillion pounds ($74 trillion).

“We again find the relief ending next spring with no solution ...