Sam Zell, billionaire real estate investor, dies at 81

What they're saying: “The world has lost one of its greatest investors and entrepreneurs,” Equity Residential CEO Mark J. Parrell said in a statement. “Sam’s insatiable intellectual curiosity and passion for deal making created some of the most dynamic companies in the public real estate industry.

• "He was a generous philanthropist and an incredible mentor and friend and will be missed by all who were lucky enough to be part of his extraordinary world."

Equity attributed his death to "complications from a recent illness," the AP reported.

Known for his charismatic presence and for making big bets, Zell's reputation as a business icon took a hit when his $13 billion acquisition of the Tribune Co. flopped, culminating in the media company's 2008 bankruptcy.

But the failed deal could not erase an empire he had started building as a student at the University of Michigan, where he was "managing the building where he lived in exchange for free rent" and later "moved on to managing other properties," according to the AP.

• After school, he partnered with U-M fraternity brother Robert Lurie to buy distressed properties.

• In the 1990s, Zell helped to popularize the real estate investment trust (REIT) structure, according to Reuters, and took Equity Residential public in 1993.
• In 2007, he sold Equity Office Properties to Blackstone for $39 billion in what Reuters called "one of the largest real estate deals ever."

Forbes estimated that Zell was worth $5.2 billion at the time of his death.