Who this entry is for — Anyone who wants to read Market Profile letters without confusing them with quantity, trade count, or minutes spent at a price.
Primary sources: J. Peter Steidlmayer and Kevin Koy, Markets and Market Logic (1986), Section I, ch. 6; Chicago Board of Trade, CBOT Market Profile®, Part I (1996).
Prerequisites
Market Logic principles and Market Profile.
Definition
In plain language — Each letter column represents an interval of the session. If the market trades a price row during that interval, the corresponding letter appears on that row.
A TPO (Time-Price Opportunity) records the opportunity to trade a given price during a specific time bracket. In the classical construction, the letters A, B, C, and so on often represented half-hour intervals.
| Element | What it represents |
|---|---|
| Vertical row | Price or group of ticks |
| Letter | Time bracket that visited the row |
| More letters on the row | More distinct brackets traded that price |
| Single print | Row visited in only one bracket, under the chosen configuration |
A letter does not measure how many times price crossed the row within the bracket, how much volume traded, or exactly how many minutes price remained there.
How to read the diagram
- Columns A, B, and C are three distinct time brackets.
- Each populated cell is one TPO: that bracket visited that price row.
- P2 contains three letters and has the highest count: in the diagram it is the TPO POC.
From data to distribution
In plain language — Compressing letters by price produces a distribution of time-bracket visits. It describes an auction that has already occurred.
The TPO count for a row is the number of brackets present. The row with the highest count may be used as the TPO POC; in a tie, the CBOT manual applies a tie-break toward the midpoint of the range.
The shape depends on:
- the session and time zone;
- bracket duration;
- price-row size;
- treatment of overnight sessions, gaps, and missing data.
Changing these parameters also changes the distribution.
Example — Price 100 is visited in brackets A, B, and D: it counts as three TPOs. If A records 5 contracts and B records 500, the TPO count does not preserve that difference; Volume Profile is needed for it.
TPO, volume, and value
In Steidlmayer's historical language, repeated rotations over time are interpreted as value development, while brief visits are treated as extremes or rejection. These are categories within the framework, observed ex post; they are not mathematically equivalent to volume and do not identify cause or future direction on their own.
Common error — Reading the historical formula “price + time = transactional volume” as a numerical identity between TPO count and volume. In operational data they remain different measures: one counts brackets, while the other measures executed quantity.
Summary card
- TPO: presence of a price in a bracket.
- Does not measure: volume, trade count, or exact minutes.
- Reproducibility: state the session, bracket duration, and row size.
Sources
- J. Peter Steidlmayer and Kevin Koy, Markets and Market Logic, Porcupine Press, 1986, Section I, ch. 6 — definition and role of the Time-Price Opportunity in the framework.
- Chicago Board of Trade, CBOT Market Profile®, Part I: Reading the Market Profile Graphic, 1996, pp. 1–13 and 44 — graphic construction, time brackets, and fairest price.