"Appetite for high-quality retail real estate is strong with cap rates and REIT stock multiples approaching historic levels and we did not believe the market accurately reflected the value of the assets," Excel Chief Executive Gary Sabin said in a statement.
The deal was announced shortly after General Electric said that Blackstone Group and Wells Fargo would buy most of the assets of GE Capital Real Estate in a deal valued at about $23 billion.
Real estate has overtaken private equity as Blackstone's most high-profile and lucrative business, and the company now has the world's biggest private real estate investment business.
Real estate accounted for 43 percent of Blackstone's economic net income in 2014.
Morgan Stanley was financial adviser to Excel, while Eastdil Secured/Wells Fargo Securities and Barclays advised Blackstone. Latham & Watkins was Excel's legal counsel. Simpson Thacher & Bartlett was the legal adviser to Blackstone.