The top is initially marked with the PSY (preliminary supply) where evidence of supply begins to emerge. That is to say, what was once an invincible looking market with no sellers, begins to show signs of some sell pressure. It is however pushed higher with the last bit of fomo buyers which creates the buying climax at BC.
With the volume climaxing at the BC, the public is reaching their maximum buying output and their orders being filled by the larger institutional players who are in control of the price. Shortly thereafter, the buying pressure succumbs to the increasing supply and thus we have an automatic reaction at AR. This forms the trading range (TR) low for now.