This analysis is purely written from an Elliot Wave perspective. There are no macroeconomics or any other economic theories involved.
SPY:
Looking at Monthly SPY, we had the completion of wave 1 in 2000. Followed by a recession in 2001-2002. We then had a pullback to the 2000 high, which then ended up double topping and then falling to lows in 2008. This is a clear ABC Flat, where a flat either ends at 1:1 retracement or a 1.272 retracement. As we can see on the chart we ended in a 1.272 retracement and began recovering again. Which resulted in a huge impulsive 3rd wave up. In Elliott Wave Theory wave 3 is the most impulsive wave of all. I've made a 5 wave subcount inside the 3rd wave, which has a extended 5th sub wave, which ends at a 2.618 extension. This is because wave 3 closed below the 1.618 extension. The 2.618 also concludes with the overall 5 waves count, where the 3rd wave ends at 2. extension. (yellow wave). This suggest that we will see a retracement back to (most likely) a 0.5 fib extension of the 3rd wave (yellow).
DOW:
To keep this short, we are seeing almost the exact same pattern with DOW. We have a 3rd wave ending at a 1.618 extension (instead of the .2 extension on the SPY.). If we count the subwaves of the 3rd (yellow) wave, we have a 5th subwave ending at a 2.618 extension like we had with SPY. We would now expect the same ABC retracement to the 0.5 Fibonacci of the 3rd wave.
Conclusion: Overall we see overbought levels with both the SPY and DOW, this will lead to a recession, which could be worse than the financial crisis in 2008 and the great depression in 1930. I expect a 35-40% drop in these indexes.