WASHINGTON (AP) - The Securities and Exchange Commission chairman, Christopher Cox, will have surgery Monday to remove a tumor and is expected to recover quickly and fully, the agency announced Friday. Cox, who became head of the SEC in August after 16 years in Congress as a California Republican, will have a thymoma removed, the agency said in a brief news release. A thymoma is a tumor on the thymus gland, which regulates development of the immune system and is located in the chest above the heart. It is not necessarily cancerous. The news release said Cox, 53, is expected...