Wal-Mart Stores, the world's largest retailer, said it has signed an agreement with China International Trust & Investment Corp., known as Citic, to open stores on China's booming eastern coast. Wal-Mart said a new joint venture with Citic, called East China Wal-Mart Stores, would open supermarkets in and around Shanghai, China's largest and richest city. Citic's main business is financial services. Wal-Mart also said it had opened a procurement center in Shanghai to buy merchandise from eastern and northern China for export. The company says it bought more than $10 billion in goods in China last year. The joint-venture supermarket deal marks the U.S. company's first foray into eastern China, although Wal-Mart already has 22 stores elsewhere in China.