Price-Level Error Correction
Use support and resistance breaks to define when a market thesis is wrong
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 5
- Confidence
- 93%
Identify the range in which buyers repeatedly support price and sellers repeatedly cap it. The lower boundary is support; the upper boundary is resistance. A move above resistance suggests that buyers now perceive enough value to pay more and can initiate an uptrend. A move below support suggests that sellers will accept less and can initiate a downtrend. Before entering or maintaining a position, define which boundary would invalidate the thesis. If price crosses that level, act rather than inventing a new story. Barry Ritholtz illustrated the rule by covering a short position in Google soon after it broke above its range; the small loss prevented exposure as the stock continued higher. The mechanism turns chart structure into a concrete error-correction and risk-management rule.
Origin
Barry Ritholtz and Louise Yamada developed this price-level decision rule during their Masters in Business discussion of support, resistance, and breakouts.
Core principles
- 01Repeated buying and selling creates observable price boundaries
- 02A breakout signals willingness to pay more
- 03A breakdown signals willingness to accept less
- 04Price levels make a thesis falsifiable
- 05Small disciplined losses protect against larger errors
How to run it
- 1
Define the range
Identify the levels where buyers have repeatedly entered and sellers have repeatedly appeared.
Pro tip Use repeated behavior rather than a single isolated price.
- 2
Set invalidation
Decide in advance which support or resistance break would prove the position wrong.
Watch out Without a predefined level, a losing thesis can turn into an open-ended story.
- 3
Observe the boundary
Watch whether price remains inside the range or moves through one of its boundaries.
Watch out A brief move can be a false breakout, so consider whether price returns to the range.
- 4
Accept the signal
Treat a valid breakout as evidence of greater willingness to pay, and a valid breakdown as evidence of greater willingness to sell.
- 5
Correct the error
Exit a position when price crosses the level that invalidates it, even if the original narrative still sounds persuasive.
Pro tip Judge discipline by following the rule, not by whether the trade was profitable.
In the wild
Ritholtz traded Google while it remained range-bound, then found himself short when the stock broke above 200. He covered around 202 or 203 rather than arguing with the breakout. The stock did not return to the old range.
→ He accepted a small loss and avoided remaining short during the subsequent rise.
Common mistakes
Arguing with the price
Continuing to defend a thesis after its invalidation level breaks defeats the error-correction mechanism.
Holding losers while clipping winners
Refusing to admit error while taking small profits can leave losses larger than gains.
Is it for you?
Best for
It is best for positions formed around a clear trading range, support level, or resistance level.
Not ideal for
It is not ideal when price has no established range or when the investor will not honor a predefined invalidation point.
From the transcript
“if the price moves up through fifteen, basically, it's suggesting that somebody out there perceives something positive about this company and is willing to pay…”
“the nice thing about charts is it gives you a place to know for sure where you're right or wrong. It it's a error correction…”
“The prices the final arborter”
From the episode
Interview With Louise Yamada: Masters in Business (Audio)
Louise Yamada