All-time high
Also called: ATH, ATL, all-time low, all time high, all time low
An all-time high is the highest price a trading instrument has ever traded at, and an all-time low is the lowest. Traders shorten them to ATH and ATL. They are the most visible prices on any chart, seen on every timeframe without drawing anything. In the ChartThread course they are historical levels, and they behave in a recognisable way.
Why all-time highs and lows act as levels
An all-time high is usually where a long rise ended, so it is often also a trend-change level: someone big sold there.
Two rules from the course apply:
- Extremes are rarely broken on the first attempt. Price often stops short of it or goes a little beyond and closes back: a false breakout.
- No one wants to be first. Near the level, and near the all-time high or low, nobody is willing to be the first to break it. On the most powerful levels volume often shrinks on the way in.
On a real market. Ethereum’s perpetual contract set an all-time high of 4,877.54 on 10 November 2021 and did not trade there again for almost four years. In August 2025 it came back three times: on 14 August it stopped 83.54 short, on 22 August it went 10.95 above and closed at 4,830.37, and on 24 August it went 80.13 above and closed at 4,778.32. The tails above 4,877.54 do not move the level: the tail of a false breakout at an extreme is not a new level.
The rule is about odds, not certainty. Bitcoin’s 2021 high of 69,198.7 failed on the first attempt on 5 March 2024, then broke on 11 March with a close at 72,153.8, the fourth day that traded above it.
What to do at a new all-time high or low
At a new extreme there is no history to the left, so there is nothing old to draw from. Two things replace it:
- The previous day’s high and low are levels. When a day goes beyond yesterday’s high and cannot close above it, that high is the level the false breakout happened at.
- A round number can be a level by itself. Only here, at an all-time high or low, a round number such as 100,000 is a level with no event behind it.
Example. A share trades at a new all-time high. Yesterday’s high was 50.00 and its low 48.00. Today price goes to 50.40 and closes at 49.70. The day could not close above 50.00, so 50.00 is the level. With a daily average true range (ATR) of 2.00, the stop is 10% of it, 0.20, so a short from the level has its stop at 50.20.
All-time highs in this course
When price returns to an old extreme, the course sizes the stop from the ATR as at any level. Before Ethereum’s attempts in August 2025 the daily ATR was 228.70, so the stop was 22.87 above the level, at 4,900.41. It held on 22 August and was taken on 24 August, while the level itself held both days. The details are in historical levels, the previous-day rule in why levels come from the daily chart, and the round-number rule in round numbers.
Questions about all-time high
What does ATH mean in trading?
ATH stands for all-time high: the highest price an instrument has ever traded at since it was listed. Its opposite is ATL, the all-time low. On a daily chart the all-time high is the highest wick on the whole history, not the highest close.
Is an all-time high a level?
Yes. In the ChartThread course an all-time high or low is a historical level. Every player sees it without drawing anything, and extremes are rarely broken on the first attempt.
What happens when price comes back to an all-time high?
Often it stops short or goes a little beyond and closes back. Ethereum came back to its 2021 high of 4,877.54 three times in August 2025 and could not close a day above it. It is not a promise: Bitcoin’s 2021 high of 69,198.7 broke on the fourth day of trying in March 2024.
Which levels do you use when price is at a new all-time high?
With no history to the left, the high and the low of the previous day are levels. A round number can also be a level by itself there, which is not the case anywhere else on the chart.