Are you looking for an edge in swing trading/long term investing? I highly suggest using market breadth!
Highlighted with vertical lines on the chart and yellow and red circles in the breadth chart (% of S&P above their 50 day MA) are all instances when breadth dropped to 50 or 30% AFTER rising from 10 to 91%. As you can see from the chart in all historical cases breadth went back up to at least 75% signaling and end to the correction/bear market.
We are currently sitting at 48ish %. If breadth goes back up above 50 to 75% then history tells us (based on collective actions of all market participants) that this signals a move to new all time high!