JEDDAH: Saudi Arabian shares plunged to the lowest level since March after oil prices dropped, following a global stock retreat over concern about the world's economy. Saudi Basic Industries Corp. and Al Rajhi Bank led the decline. National Industrialization Co. fell for a fourth straight day. SABIC fell as much as 2.2 percent to SR100.50, the lowest price since March 23. Al Rajhi dropped as much as 2.4 percent to SR71.75, the largest intraday loss in two months. National Industrialization, the petrochemicals maker known as Tasnee, declined as much as 3.4 percent, the steepest drop since May 7, to SR40.30. The Tadawul All Share Index fell 1.7 percent to 6,432.25 Saturday at close, the lowest level since March 26, bringing its three-day retreat to 3.4 percent. All 15 industry groups tumbled. "The Saudi market is reacting to the US and global markets ending the week on a negative note," said Fuad Aghabi, investment director at Ajeej Capital in Riyadh. "Weak international economic data and the global stock price movements last week are probably giving the local investor indicators that the global economy maybe hitting a soft patch in its road to recovery." Oil tumbled the most in four weeks after unidentified senior OPEC and industry officials said Saudi Arabia will raise oil production to 10 million barrels a day next month. Oil in New York dropped 2.9 percent Friday. Crude for July delivery settled at $99.29 a barrel on the New York Mercantile Exchange. Prices declined 0.9 percent this week. The MSCI All-Country World Index slid 1.4 percent Friday. The Standard & Poor's 500 Index dropped 1.4 percent and the Stoxx Europe 600 index slumped 1.3 percent.