Emerging-market currencies and stocks fell on concern the ceasefire between the US and Iran is on the brink of collapse, while a slump in South Korean shares also weighed on sentiment.

MSCI’s index of EM currencies was set for its biggest one-day loss since March, with the South Korean won leading declines. Currencies of oil importers including South Africa’s rand and Indonesia’s rupiah underperformed, with the latter falling to a record low against the dollar.