Complex sentence: Hammer owned a considerable amount of Church and Dwight stock in the 1980s and served on its board of directors, but the company's brand name, Arm & Hammer, did not originate with Armand Hammer.
Split into simpler sentences: Hammer owned a considerable amount of Church and Dwight stock in the 1980s and served on its board of directors. The company's brand name, Arm & Hammer, did not originate with Armand Hammer.