Stocks across the Middle East tumbled as the easing of sanctions against Iran raised the prospect of a surge in oil supplies to a market already reeling from the lowest prices in more than a decade.
Shares in Tehran gained.
Saudi Arabia’s Tadawul All Share Index dropped 5.4 percent to its lowest level since March 2011.
Abu Dhabi’s ADX General Index fell into a so-called bear market.
Iran, home to almost 10 percent of the world’s proven oil reserves, is starting preparations to boost exports after the United Nation’s nuclear agency on Saturday said the country has complied with the terms of an international agreement to curb its nuclear program.
That threatens to put further pressure on prices, hurting the oil-dependent economies of the GCC.