Joseph Azrack helped Citigroup Inc. build a $13 billion portfolio of commercial real estate that has plummeted in value since his departure from the bank in June 2008. The portfolio may soon be taken over by Apollo Global Management LP. Its prospective manager: Joseph Azrack. Apollo and Australia’s Macquarie Group are the finalists in the bidding to take over Citigroup’s real-estate investment unit, known as Citi Property Investors, according to people familiar with the matter. Citigroup is selling its real-estate investment unit as it seeks to focus on core businesses such as retail banking and investment banking. The unit raised money from pension plans, wealthy individuals, and Citigroup itself to build and buy property around the world.