In trading jargon, ATH stands for All-Time High.
A market makes a new all-time high if its price action rises above the previous all-time maximum price. There is no other requirement for timeframe, patterns or any special technical setup. Even if the market retraces abruptly, the new ATH still counts.
The Bitcoin ATH
On the bitcoin-dollar market, an ATH will happen when the price rises to anywhere over 20k USD.
ATH jargon term
ATH is a term that you will find used in legacy trading as well, it is not specific to crypto.
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