Saudi Arabia's shares slumped the most in almost eight months on investor concern that oil prices may retreat amid signs the global economic recovery is slowing.
Saudi Kayan Petrochemical Co, the company 35 per cent-owned by Saudi Basic Industries Corp, lost 6.5 per cent after its first-quarter loss widened.
Saudi Arabian Fertilizer Co., the company known as Safco also part-owned by Saudi Basic, tumbled to the lowest since February.
Saudi Arabia's Tadawul All Share Index fell 2.3 per cent, the most since Aug-ust 20, to 7,348.33, at the 3.30pm close in Riyadh.
Crude oil for May delivery fell 0.5 per cent last week to $102.83 a barrel (Dh377.71) on the New York Mercantile Exchange after Saudi Arabia's oil minister said the kingdom is determined to see lower prices. The world's biggest oil exporter derives more than 90 per cent of public revenue from oil exports.
"There is a fear that the global economy is slowing down and with it could take oil prices down too," said Nabil Farhat, a partner at Abu Dhabi-based Al Fajer Securities.
"Saudi Arabia will stand to lose if this happens because it has committed a large budget expenditure, which means that it could have a large but workable budget deficit."
Saudi companies started reporting first-quarter financial results this month. Saudi Kayan lost the most since January 17, falling to 17.4 riyals in its tenth day of declines, the longest stretch of losses on record, according to data compiled by Bloomberg.