What is a double top?
A double top forms when price rallies to a high, pulls back, rallies to roughly the same high again — and gets rejected a second time. The two peaks with a trough between them draw an 'M' on the chart. The trough's low is the neckline; a close below it completes the pattern.
Two rejections at the same level is direct evidence of supply: somebody is willing to sell size there, and buyers failed to absorb it twice. The second failure matters most — momentum traders who bought the retest of the high are now trapped, and their stops sit below the neckline.
Double tops are among the most common reversal structures in crypto because round numbers and prior all-time highs act as natural sell zones where the pattern repeatedly forms.