Simon Property Group is the second-largest real estate investment trust in the United States. Its portfolio includes an interest in 229 properties: 134 traditional malls, 70 premium outlets, 14 Mills centers (a combination of a traditional mall, outlet center, and big-box retailers), 6 lifestyle centers, and 5 other retail properties. Simon's portfolio averaged $739 in sales per square foot in 2024. The company also owns a 22% interest in Klépierre, a European retail company with investments in shopping centers in 14 countries, and joint-venture interests in 33 premium outlets across 11 countries.