Market profile is a way of organising a session by time rather than by the clock — plotting which prices the market visited in each half-hour bracket, and building a distribution from them. It was developed at the Chicago Board of Trade in the 1980s and remains one of the standard frameworks for describing how a session was traded.
A market profile chart is assembled from TPO units — time price opportunities. The construction is mechanical:
The result is a horizontal histogram lying on its side, where the width at each price is the number of half-hour periods that price was visited. A price touched in eight brackets is eight letters wide; a price touched once is one letter wide.
What the chart measures is acceptance over time. A price the market kept returning to across the session grows wide. A price it touched once and left stays narrow.
Three reference points do most of the work in a market profile reading.
Initial balance (IB) — the price range established in the first two half-hour brackets, conventionally the first hour of trade. On NSE that is 09:15 to 10:15 IST. The IB is used as a reference for the rest of the session: whether the range extends beyond it, and by how much, is the most common way market profile traders describe a day.
Value area — the band of prices containing roughly 70% of the session’s TPOs, centred on the point of control. It describes where the session did the bulk of its business.
Point of control (POC) — the price with the most TPOs, meaning the price visited in the largest number of brackets. Note that this is a different measurement from a volume profile’s POC, which is the price with the most traded volume. The two often sit at different prices in the same session.
Market profile literature classifies sessions by how the range developed relative to the initial balance. These are descriptions applied after the fact, not categories that can be known at the open.
This is the distinction that causes the most confusion, because the two charts look similar and share vocabulary.
| Market profile | Volume profile | |
|---|---|---|
| Unit | TPO — one letter per half-hour bracket per price | Traded quantity at each price |
| Measures | How long price spent at a level | How much traded at a level |
| POC | Price visited in the most brackets | Price with the most traded volume |
| Needs | OHLC per bracket | Tick or level data with volume |
The two disagree in a specific and useful way. A price where the market sat quietly for hours on thin volume is wide on a market profile and narrow on a volume profile. A price where an enormous quantity changed hands in a few minutes is the reverse. Neither is more correct — they answer different questions.
See volume profile explained for the volume-based construction.
The framework was designed for continuous futures sessions and transfers to Indian markets with a few adjustments.
The bracket schedule. With trading from 09:15 to 15:30 IST, the Indian equity session divides into thirteen half-hour brackets — the last one running only fifteen minutes. Most implementations either treat the final bracket as a short period or fold it into the previous one.
The initial balance is the 09:15–10:15 range. Because Indian markets open with a pre-open auction and carry substantial overnight gap risk from global markets, the first hour frequently establishes a wide IB relative to the eventual day range.
Expiry days distort the shape. On weekly index expiry, activity concentrates around strikes, and index profiles can develop structure that reflects option positioning rather than the underlying’s own trading range.
To be precise about what this platform does and does not draw: VolumeLens renders volume profile — volume-at-price — and does not currently draw TPO letter charts. Session profile, fixed range profile, point of control and value area are all computed from traded volume on live NSE data.
For traders who work primarily from acceptance and value rather than from letter counts, the volume-based profile covers most of the same ground, and it does so using the quantity that actually changed hands. If you specifically need TPO letters, that is a distinct chart type and this is not it.
A method of organising a trading session into half-hour brackets and plotting which prices were visited in each, using TPO (time price opportunity) letters. The resulting distribution shows how much of the session was spent at each price, rather than how much volume traded there.
Time price opportunity. One TPO is one half-hour bracket in which a given price traded. A price visited in five brackets has five TPOs and is drawn five letters wide.
The price range established in the first two half-hour brackets of the session — the first hour of trade, which on NSE is 09:15 to 10:15 IST. Whether and how far the session range extends beyond the initial balance is the basis of the classic day-type classifications.
They measure different things and are not substitutes. Market profile measures time spent at a price; volume profile measures quantity traded at a price. A quiet level held for hours looks significant on a market profile and unremarkable on a volume profile, and vice versa.
No. VolumeLens renders volume profile — session and fixed range volume-at-price with point of control and value area — on live NSE data. It does not currently draw TPO letter charts.
Yes. The framework is instrument-agnostic and applies to any continuously traded session. The NSE equity session divides into thirteen half-hour brackets, with the initial balance running 09:15 to 10:15 IST.