Brennan Investment Group | 9,804 followers on LinkedIn. Owners of Properties. Creators of Value. | Brennan Investment Group, a Chicago-based private real estate investment firm, acquires, develops, and operates industrial properties in select major metropolitan markets throughout the United States. Since 2010, Brennan Investment Group has acquired or developed over $6.5 billion in industrial real estate in 30 states. The company’s current portfolio spans 29 states and encompasses approximately 57 million square feet.