He sold his real estate firm, Equity Office, to Blackstone Group for $39 billion near the peak of the market. This was back in February 2007—only months before real estate credit markets started to spiral out of control.

He's doing it again.

At the end of October, his real estate fund, Equity Residential, agreed to sell more than 23,000 apartment units to Starwood Capital for $5.4 billion. The sale represents over 20 percent of the Equity Residential portfolio.

The fund plans to sell another 4,700 apartment units in the near future. Most of the proceeds will be returned to investors in the form of a dividend sometime next year.