Reading a TPO chart

The construction rule fits in one sentence: within its thirty minutes, a period prints its letter once on every price row it touches, and never twice, no matter how many times it comes back. Trade at 5,636 for one second during period C and a C prints there; sit at 5,636 for the entire period and it is still that same single C. Press each period against the price ladder this way and the session becomes rows of letters. A row three letters long held trade in three separate half hours; a row twelve letters long was doing business nearly all day.

Rules on paper are cheap; watching them run is what makes the levels stop feeling invented. The sandbox in this section replays one ES session, one 30-minute letter at a time, and recomputes three numbers after every period: POC, value area and Initial Balance, the three names you are about to earn. Press play, scrub back and forth, and notice that nothing in the side panel is drawn by opinion. Every number falls out of where the letters landed.

Run your eye down a finished profile and one row is longest. That row is the Point of Control, POC: the price where the most 30-minute periods did business. It is the clearest time-based measure of acceptance in that profile. Do not confuse it with VPOC, which measures contracts traded rather than periods present.

Ties happen. When two rows share the maximum count, convention hands the POC to the row closer to the center of the profile's range, on the logic that the middle of the day's business is a better candidate for fairest than an edge. And one naming note before later chapters lean on it: this level has a volume-built twin, the price where the most contracts actually traded, called the VPOC. Most days the two sit within a few ticks of each other, and the trap in section 02 already told you why the days they drift apart deserve your attention.

One row is the fairest price; the next question is how far around it fairness stretches. The convention: the value area is the tightest band of rows around the POC holding roughly 70% of the session's TPOs, and its edges get names of their own, VAH at the top, VAL at the bottom. Seventy is not a magic number. It is the auction borrowing the statistician's habit of one standard deviation, about 68% of a bell curve, rounded to something a trader can keep in his head.

The profile that runs with this section is a full ES session on 4-point rows: thirteen periods, A through M, 68 TPOs in total. Count any row yourself. Every level in this section and the next is computed from that one picture, and each of its labels will be earned before the chapter ends.

Go back to the profile in section 04 and look only at A and B. Together the first two periods span 5,620 to 5,640, and that first hour has a name of its own, the Initial Balance. The metaphor inside the name is honest: it is the market's opening attempt at a fair range, negotiated mostly by day traders and locals while slower money is still deciding. Everything printed after 09:30 Chicago is a verdict on that attempt.

Width is the tell. A narrow IB is a flimsy frame: the market took a full hour to agree on almost nothing, participation is thin, and one determined institutional order can reprice the whole structure, so the odds of the day trending out of it go up. A wide IB means size showed up in the first hour and fought to a standstill; leaving a frame that wide costs real money, and such days more often spend themselves rotating inside it.

Whenever a later period prints even one letter beyond the IB, that is range extension: the auction outgrowing its first frame. In that same profile, C nudged over 5,640, then D and E drove the tape to 5,656, three consecutive periods of extension up before the afternoon rotated back through the middle. One letter poking out is a probe. Letters that stay out and build on each other are the day changing character.