Macerich is a self-managed Real Estate Investment Trust headquartered in Santa Monica, California. It is the third-largest owner and operator of shopping centers in the United States.It traces its antecedents to the MaceRich Real Estate Company founded in New York in 1964 by Mace Siegel and Richard Cohen who combined their first names to name their company. After years of buying and owning shopping centers privately, in 1994 the company went public as "The Macerich Company".