ATH

ATH stands for "all-time high" — the highest price a stock, index, cryptocurrency, or other asset has ever traded at since it started trading. If a stock has been public for ten years and its highest print during that decade was $142.50, that number is its ATH until the price closes above it.

Traders track ATHs because price behaves differently once it moves into territory with no prior trading history. Below an all-time high, there's a record of past buyers and sellers at every level, which can create visible support (where buyers stepped in before) and resistance (where sellers showed up before). Above the ATH, that map disappears — every dollar the price moves is a new record, with no past price memory to reference.

The nuance that trips people up is treating an ATH as a fixed ceiling. It isn't a rule or a barrier, just a historical fact. Plenty of assets sit at their all-time high and simply keep going, sometimes for a long stretch, because a new high doesn't come with a chart pattern telling you to stop — the pattern is broken. Others reverse hard, since a new record can attract profit-taking or run out of buyers. Both outcomes are common, which is exactly why an ATH alone tells you very little about what happens next.

It's also worth noting ATH is a running fact, not a fixed one — the moment price makes a new high, the old ATH is replaced. So the term always refers to whatever the current record is, not a specific number that stays true forever.