1. Monthly Chart shows the same RSI oversold conditions as the high in 2007 time-frame (79 RSI) that led to the 2008 downturn.
a. Current chart shows the same oversold conditions in 2018 (80 RSI) which are leading to the now late 2018/19 downturn.
b. Retracement was roughly 50% during this past market collapse because support were the 2002/03 levels and RSI of 17.9 indicated severe oversold conditions.
2. After 2008 consolidation the new support level were the lows of 2002/03. (Big Psychological Factor for Traders to Re-enter Bearish Market)
a. Future chart shows the new support level will be the 2015/16 support.
b. Retracement lines up with the Fibonacci retracement of roughly 38% where support from the 2015/16 levels will prevent the market from correcting to the 50% levels of 2008.
The time-span was 518 days during the 2007/2008 retracement.....which led me to conclude that by January of 2020 the market should begin recovering after finding the 2015/16 support and showing oversold RSI conditions.
Mere speculation of course since past performance does not reflect future results, so please don't bet your life savings.