The chart shows the Inverted Yield Curve vs S&P500 both on logarithmic scale. The Yield Curve start to invert when US start to raise up interest rate, and Yield Curve start to recover when short term rate is higher than longer term rate. It's not accurate to say that Yield Curve is indicator to recession or market crash. Because there still a 1~3 year periods of market rally after Yield Curve inverted before it went bust. So to be accurate the market start to dwindle down right after the Yield Curve back to normal, not after Yield Curve start to invert. So we still have a brief period to invest in stock until after rate reach high enough to be un-investable, then we should be worry about market crash.