Who this is for — Anyone using VAH, VAL, and POC who needs to distinguish a band calculated from volume from one derived from TPOs.
The Value Area (VA) is a central price interval selected by an algorithm applied to a profile. Its upper boundary is called VAH (Value Area High) and its lower boundary VAL (Value Area Low).
In plain terms — The Value Area label does not imply one unique calculation. Before comparing two charts, identify the data, percentage, starting point, and expansion rule.
Volume Value Area and TPO Value Area
| Variant | Input data | Possible criterion |
|---|---|---|
| Volume VA | Quantity traded at each price | Interval reaching a target share, often about 70% |
| TPO VA | Number of time brackets at each price | Count or rotations under the adopted convention |
The 1996 CBOT manual explicitly distinguishes a Volume Value Area containing 70% of session volume in its example from a TPO Value Area determined by rotations. It does not treat them as synonyms.
Software and data vendors can use different algorithms: expansion from the POC, comparison of pairs of rows, different tie-breaks, or configurable percentages. Even with the same threshold, two implementations can produce different VAH and VAL values.
Parameters to declare
In plain terms — A Value Area is reproducible only when another person can reconstruct it from the same data and rules.
- instrument, contract expiry, and venue;
- session and time zone;
- TPO or volume;
- row size or price aggregation;
- target percentage, if used;
- expansion algorithm and tie-break;
- completed or developing profile.
Example — “70% Volume VA, 09:30–16:00 ET session, 0.25 rows, expansion from the Volume POC” is a comparable specification. “Today’s Value Area” is not.
Interpretation and limits
VAH and VAL describe the boundaries of the calculated area; they are not automatically support and resistance. An open outside the previous Value Area, a move back inside, or remaining outside are contextual observations, not complete signals.
Typical mistake — Buying VAL and selling VAH without defining the regime, invalidation, and data. During a directional session, the profile and Value Area can migrate as price extends the range.
Summary card
- VAH / VAL: boundaries of the calculated interval.
- 70%: frequent volume convention, not a universal law.
- Before use: distinguish TPO VA from Volume VA.
Sources
- Chicago Board of Trade, CBOT Market Profile®, Part I: Reading the Market Profile Graphic, 1996, p. 33 — example and distinction between Volume Value Area and TPO Value Area.
- J. Peter Steidlmayer and Kevin Koy, Markets and Market Logic, Porcupine Press, 1986, section I, chapter 6 — historical relationship between price, time, and profile construction.