Every volume profile has three landmark lines: the POC in the middle, and the VAH and VAL marking the edges of the value area. This article covers the pair at the edges — what the value area actually is, how traders read acceptance and rejection at its borders, and the famous "80% rule" with its honest fine print.
(Quick note: nothing here is financial advice. Value area levels describe where trade happened — they don't guarantee where price goes next.)
What the value area is
Take any period — usually a session — and stack its volume by price. The value area is the band around the POC that contains roughly 70% of everything that traded. Its upper edge is the Value Area High (VAH); its lower edge the Value Area Low (VAL). The logic: this is where buyers and sellers agreed enough to do most of their business — the market's "fair price" for that period. Above the VAH, price was interesting enough that someone kept paying up; below the VAL, cheap enough that someone kept selling down. Both edges are where agreement ended.
Why 70%? It's a convention, borrowed from the idea of one standard deviation of a bell curve (~68%). Markets aren't bell curves, and the percentage is a setting you can change — worth remembering when levels from different platforms don't quite match.
Where the idea comes from
The vocabulary — POC, value area, single prints — comes from Market Profile, developed by J. Peter Steidlmayer at the Chicago Board of Trade in the 1980s. His version measured time at price (TPO letters); modern platforms usually measure volume at price, since exchange volume data is now tick-level. The two mostly agree but not always — a time-based POC and a volume-based POC can sit at different prices. Same language, slightly different rulers.
Acceptance vs rejection at the edges
The most useful read at the VAH or VAL is a simple question: is price being accepted outside value, or rejected?
- Rejection — price pokes outside, finds no interest, and snaps back inside quickly, leaving wicks and thin volume behind. The auction tried a new price and failed; rotation back toward the POC or the other edge becomes the working idea.
- Acceptance — price breaks the edge and stays there: time passes, volume builds, a new node starts forming outside the old area. That's the market agreeing value has moved — continuation, not reversion.
Time plus volume outside the edge is the tell. A break alone tells you very little.
The 80% rule
The best-known value area play: if price opens outside the prior day's value area and then re-enters and holds inside (the classic version says two consecutive 30-minute periods), the rule claims roughly an 80% chance it rotates all the way across the value area to the opposite edge.
The honest fine print: the number comes from Market Profile research in the late 1980s — Jim Dalton's circle, pit-session data, time-based profiles. It has never been rigorously verified in modern markets, community backtests are mixed, and the POC often stalls the rotation halfway. What survives scrutiny is the structure, not the statistic: re-entry plus holding inside gives a defined idea, a target (the far edge), and a clear invalidation. Traders use it as that — a framework, not a probability.
Where price opens matters
Value area logic starts before the first trade of the day. An open inside yesterday's value hints at a balanced, rotational day — edges get faded, POC acts as the magnet. An open outside value means the market is imbalanced: either it re-enters (the 80% setup) or it builds acceptance outside and trends. The further the open from value, the less business the market has with yesterday's prices — and the more careful the fade.
Yesterday's levels and naked ones
Prior-session VAH, VAL, and POC keep working as reference levels after the session ends — and levels price never came back to touch get a special name: naked. A naked POC is the classic magnet-style target. Overlapping value areas across several days stack into strong balance zones; value areas migrating higher or lower day after day are the profile's way of drawing a trend.
The honest limits
- Trend days ignore all of it. On a real trend day, price leaves value early and never looks back — edge-fading is exactly the wrong plan. The tool describes balance; trend is the absence of balance.
- Your session template moves the lines. A profile of the full electronic session (ETH) and one of the day session only (RTH) produce different value areas. If your levels don't match someone else's, check the session first.
- Platforms disagree slightly. The expansion algorithm (how rows are added around the POC), the row height, and the 70% setting all nudge VAH/VAL a tick or two. Treat the edges as zones, not laser lines.
- Reactions need confirmation. Levels often react on the second test rather than the first — watching how price behaves at the edge beats blind limit orders sitting on it.
Value areas in ATAS
In ATAS the profile tools draw all of this: the Volume Profile / TPO indicator builds session, weekly, or custom-range profiles with the value area shown as lines or a shaded band and labels on VAH and VAL; a fixed-range version profiles any stretch of chart you drag over; and Dynamic Levels shows the developing value area of the current session updating live — useful for watching acceptance build in real time. Profiles can also be built from delta or bid/ask data instead of plain volume, which is where profile logic meets order flow.
What you need
Any platform with a volume profile shows VAH, VAL, and POC. ATAS has the full toolset built in — the free demo is enough to mark yesterday's value area and watch today's auction interact with it.
The bottom line
The value area is where roughly 70% of a period's business happened; VAH and VAL are its edges, and the edges are where the information is. Rejection there points back into the range; acceptance beyond them points at migration. The 80% rule is a classic framework with an unverified number attached — take the structure, leave the statistic. Add the session context and yesterday's naked levels, and the value area becomes one of the clearest maps a futures chart offers — a map of where agreement lives, not a promise of where price must go.