The upper bound of the channel represents one standard deviation away from the 300 daily high regression line. The SPY daily candles have remained in the upper half of the regression channel for quite some time. In theory, the price should revert down to the center lines at least. However, there is a scenario where the price can move sideway and wait for the center lines to catch up with the price. Expecting a price correction down to $325 at least. The Shiller PE of SPY is still above 30, so the warning is still there. I don't think SPY can or should reach a new high due to uncertainties related to election and covid-19. This is my humble opinion only and should not be used to constitute your trades :)