Simpson Housing doesn't build apartments in the mythical metropolis of Springfield ( d'oh ), but it is a major force behind multifamily housing in the US. The holding company invests in, develops, constructs, acquires, and manages residential properties, primarily luxury apartment communities around the country. Its Simpson Property Group subsidiary, established in 1948, oversees a $3 billion portfolio of about 100 apartment and senior communities in about a dozen states. Great West Contractors provides construction management services. The Michigan State Employees' Retirement System owns about 45% of the company; the Alaska Permanent Fund owns another 45%.