Investors are no closer to understanding how the opening of Saudi Arabia’s stock market will work than they were in August, when the country published draft rules on the plan. Eleven weeks before the deadline that the Middle East’s largest bourse set itself to give foreigners direct access to the market, the Riyadh-based Capital Market Authority has yet to explain how it will square the new rules with existing restrictions on foreign involvement in Saudi businesses. The lack of clarity underscores the difficulty the world’s biggest oil exporter has in giving outsiders greater influence. The kingdom is seeking to attract increased investment to the $521 billion stock market without angering conservatives dedicated to preserving the nation’s Islamic roots.