Saudi Arabian stocks, opened last week to foreign investors for the first time, sank the most in 12 weeks following a decline in the price of crude oil. The Tadawul All Share Index retreated 1.7 percent to the lowest level in more than two months. Al Rajhi Bank, the lender with the biggest weighting on the gauge, led the decline with a 2.9 percent drop, followed by National Commercial Bank’s 3.1 percent slide. Saudi Basic Industries Corp., the world’s top petrochemicals manufacturer by sales, dropped 2.2 percent. “It’s a reaction to the weakness of oil prices on Friday,” Sebastien Henin, the head of asset management at The National Investor in Abu Dhabi, said by telephone on Sunday. “Investors are selling as there wasn’t the spike they were expecting after the market opened up for direct foreign investment.” Foreign ownership of the kingdom’s shares was little changed at the end […]