The Real Estate sector - here represented by iShares U.S. Real Estate ETF (IYR, in orange), Simon Property Group (SPG, in purple), Equity Residential (EQR, in red), - can sometimes act as an early indicator against the broader market (here represented by the DJIA in gray, and the NASDAQ [IXIC] in black)... falling from peaks in 1998, Feb 2007, Mar 2015, Nov 2017.