Sam Zell, a man generally regarded as a genius within commercial real estate, has died today at his home due to complications from a recent illness, the family of Equity companies has announced. Zell, 81, was chairman of Equity Group Investments, Equity LifeStyle Properties, Equity Residential, and Equity Commonwealth. 

A self-made entrepreneur, over the course of his 60-plus-year career Zell launched and grew hundreds of companies that spanned numerous industries across the globe. But he was most widely recognized for his critical role in creating the modern REIT, which today is a more than $4 trillion industry.

Zell began his career by managing student housing apartments as an undergraduate at the University of Michigan and his first employee was Bob Lurie, a fraternity brother. In 1968, Zell founded Equity Group Investments, a private investment firm headquartered in Chicago. A year later, Lurie joined him as a partner at EGI. Together, they built an empire, branching out from real estate to invest across industries in the 1970s and 1980s, with the partnership ending in 1990 when Lurie died of cancer – just before Zell launched what became some of the most successful REITs in history: Equity Residential, one of the largest apartment REITs,  Equity LifeStyle Properties, a manufactured home community and resort REIT, and Equity Office Properties Trust, which was the largest office building owner in the country and the first REIT in the S&P 500 when it was sold in 1997 for $39 billion in the largest leveraged buyout in history at that time.