Complex sentence: He became district manager of the Southern New England Telephone Co., then corporate planning manager for American Cement, and then relocated to San Francisco, California, climbing the corporate ladder to become a Senior Vice-President at the Pacific Stock Exchange.
Split into simpler sentences: He became district manager of the Southern New England Telephone Co., then corporate planning manager for American Cement. He subsequently relocated to San Francisco, California, quickly climbing the corporate ladder to become a Senior Vice-President at the Pacific Stock Exchange.