The first hour is a declaration
When a session opens, the first 60 minutes are not random. Institutions are adjusting overnight positions. Orders that built up after the prior close are hitting the market simultaneously. The range that emerges from that opening activity — the highest and lowest price reached in the first hour — is the market's opening declaration.
That range is the Initial Balance. IB High and IB Low are the two horizontal lines that define it. Once the first hour closes, those levels do not move. They become the spatial reference frame for the rest of the session — every move afterward is either inside that range or breaking out of it.
The construction
The IB is derived from the first four 15-minute brackets of the session.
The three zones
The IB range is not just a high and a low — it has internal structure. Dividing the range into three equal zones gives a finer read on where price is positioned within the opening balance.
Inside versus outside
As long as price stays between IB High and IB Low, the session is accepting the opening range. Buyers and sellers are both active within the space the first hour defined. The session is balanced — debating value rather than breaking out of it.
When price moves above IB High after the first hour, the opening ceiling is rejected. Buyers pushed beyond what the first hour established. When price moves below IB Low, sellers broke the floor. Both events are directional statements — the market is no longer accepting the opening range as sufficient.
Why it matters for options
Before taking any position, knowing where IB High and IB Low sit tells you the structural context of the session. A call entry above IB High means price has already broken the opening ceiling and you are entering into an established extension. A call entry inside the IB means price has not yet made the directional statement — the break is still ahead.
The IB levels also act as reference points for how far a move has traveled. A position entered at IB Low that reaches IB High has crossed the entire opening range — a meaningful move with a known spatial reference. That is different from a position where the distance to target is undefined.
On any chart
Mark the high and low of the first 60 minutes on your chart and draw two horizontal lines. Those are your IB High and IB Low for the session. Most charting platforms let you set a session range overlay or you can draw them manually at market open.
Once marked, everything that happens for the rest of the session has a frame. Price is either inside the opening range, testing its edges, or breaking out. That spatial context is what Market Profile adds to any signal — not a new entry, but a clearer picture of where in the session structure that entry is occurring.