JEDDAH: Saudi shares rose the most in a week as first-quarter earnings improved and crude oil's rally to a 30-month high increased confidence in the petrochemicals industry. The stock benchmark Tadawul All Share Index rose 0.52 percent to close Saturday at 6,608.60 points, the biggest gain since April 2. "Traders are focusing on the positives by continuing to build positions at the start of first-quarter results," said Fuad Aghabi, investment director at Ajeej Capital in Riyadh. "This is further supported by gains in the international equity and oil markets." National Industrialization Co. (Tasnee) advanced 1.2 percent and Al Rajhi Bank added 0.7 percent. Al Rajhi advanced to SR77.25, the highest level since April 4, while Tasnee climbed to SR34.3. Saudi Industrial Investment Group increased 1.9 percent, the biggest gain in a week, to SR24.3. "Those who are under-exposed to petrochemicals will not want to miss the train, as the market expects more surprising numbers," said Amro Halwani, a senior trader at Shuaa Capital PSC in Riyadh. Kingdom Holding Co. climbed the most in almost three weeks after the Saudi Arabian investment company and Bahrain Telecommunications Co. signed an agreement with Mobile Telecommunications Co. to buy the Kuwaiti company's 25 percent stake in Zain Saudi Arabia. The shares rose 1.7 percent, the biggest gain since March 20, to SR9.25.