IG Group, Britain’s biggest spread-betting company, saw its shares fall on Tuesday following reports that Japanese regulators may be looking to limit the amount of leverage that can be used by retail foreign exchange speculators in Japan.

Details and timing of the changes are unknown at present but IG, which entered the Japanese market last year with the acquisition of a majority stake in FXOnline, an online foreign exchange company, said any move to introduce a leverage cap would only affect a minority of its clients there and would not have a big impact on earnings.