IF my PREDICTION is right and technical chart is better way to detect:
Using 2008 as a market cycle.
Peak. 2007 and 2017.
Market plunge. 2008 and 2018.
Recover. 2009, ? (let the chart do the work).
Every market is different. Today the market is fundamentally not sound but technically sound. Again, it is based on a prediction that may not materialize. The market only crashes when both fundamentals and technicals are bad.
As in stocks, the over-value market could stay for a long while.