Unfinished auction on a footprint chart explained: what the label means at the high and low

What an unfinished auction on a footprint chart means

An unfinished auction on a footprint chart is a label for a bar, or a profile, whose highest or lowest price row shows traded volume on both the bid side and the ask side. In other words, at the extreme price, aggressive sellers and aggressive buyers both executed trades. The label describes what printed at that price. It does not show who is still waiting there, and it does not tell you that price will come back to that level.

This article defines the term, explains how the label is applied at the auction high and low, and separates what the displayed numbers show from what traders often read into them.

Footprint terminology you need first

A few terms come up every time unfinished auctions are discussed:

• Bid volume: contracts that traded at the bid price, meaning a market sell order hit a resting buy order.
• Ask volume: contracts that traded at the ask price, meaning a market buy order lifted a resting sell order.
• Auction high and low: the highest and lowest prices that actually traded within the bar or profile you are looking at.
• Extreme row: the top or bottom row of the footprint, where the auction high or low printed.
• Finished auction: the opposite label, used when the extreme row shows zero volume on one side.

If the difference between a footprint cell and a candlestick body is still new to you, the article on footprint chart vs candlestick chart for futures covers that first.

How the label is applied at the auction high and low

The check is simple and only involves two rows per bar: the top one and the bottom one.

1. Find the highest price row of the bar.
2. Read the bid number and the ask number in that row.
3. If both are greater than zero, the high is labeled unfinished.
4. Repeat for the lowest price row to classify the low.

A quick illustration on ES, where each row is one 0.25 tick:

• Top row of a bar reads 14 x 22 (bid x ask). Both sides traded, so the high is labeled unfinished.
• Top row reads 0 x 9. Only one side traded at the extreme, so the high is labeled finished.
• Bottom row reads 31 x 6. Both sides traded, so the low is labeled unfinished.

The numbers are illustrative only. They show how the label is assigned, not what any particular session looked like.

Where definitions differ

Educators and charting vendors agree on the core idea, both sides trading at the extreme, but they do not always agree on the details. Some only label a high finished when one specific side is zero, others accept either side being zero. Some apply the label per bar, others only to the session or profile high and low. Before you compare notes with another trader or read a course, confirm which convention they use. Two people can look at the same chart and disagree on the label simply because they define it differently.

The term itself comes from auction market theory, where a price extreme that traded without a clear rejection is considered incomplete. It is a reading convention, not an exchange status. The exchange records trades, it does not tag any auction as finished or unfinished.

What the displayed volume shows

The two numbers in an extreme row tell you three concrete things:

• How many contracts traded at that price on each side during the bar.
• That at least one aggressive buyer and at least one aggressive seller executed at the extreme.
• The relative size of each side at that price, which you can compare with the rows just inside it.

In Sierra Chart, these numbers come from the Numbers Bars study, which builds the footprint from recorded trades. The Numbers Bars documentation describes the available display columns. Check the study settings and that documentation to see whether your version offers a built-in highlight for the extreme rows. If you do not find one, reading the top and bottom rows manually takes a few seconds per bar.

What the displayed volume does not show

This is where most misreadings start. An unfinished auction label does not show:

• Resting orders. The footprint records executions. Limit orders that sat above the high or below the low without trading are invisible here. For resting liquidity you need depth data on a DOM, which is a different view, covered in Sierra Chart DOM columns explained.
• Intent. Both sides trading at the high tells you nothing about why. Hedgers, spread traders, stops and algorithms all print in the same cells.
• A future revisit. The popular idea that markets tend to come back to unfinished highs and lows is a belief some traders hold, not something the label measures. Treat it as a hypothesis you can study in replay, not as a fact.
• Significance. On a 1-minute ES chart, a large share of bars will carry an unfinished high or low simply because liquid markets trade both sides at most prices. A label that appears often carries little information on its own.

The same caution applies to large numbers at the extreme. A big print with little price movement is a separate concept discussed in what is absorption on a footprint chart.

Settings that change whether a bar gets the label

Because the label depends on exactly two cells, anything that changes those cells changes the result.

Row size and price increment

If you group several ticks into one row, the extreme row now covers several prices. On NQ, where the tick is 0.25, a footprint set to 1-point rows combines four ticks into each row. The top row can show bid and ask volume even if the single highest tick traded on only one side. A high that would be finished at one-tick resolution can appear unfinished when rows are grouped. For an unfinished auction reading, use one tick per row: 0.25 on ES and NQ, 1 on YM, 0.10 on RTY, 0.01 on CL.

Data granularity

Bid and ask classification needs tick by tick data. In Sierra Chart, set Global Settings >> Data/Trade Service Settings >> Intraday Data Storage Time Unit to 1 tick, as described in the tick by tick data configuration page. With coarser stored data, historical bars can show volume without a reliable bid and ask split, and the extreme rows cannot be classified correctly. The guide on Sierra Chart footprint tick data requirements explains how to verify historical cells.

Bar type and period

A 1-minute bar, a 500-volume bar and a full session profile each have their own high and low. The same price can be the unfinished high of a 1-minute bar and an unremarkable interior row of the session. Always state the timeframe when you note an unfinished auction.

Forex instruments

Spot EURUSD has no single centralized trade tape, so a broker feed cannot give you a consistent exchange-wide bid and ask split. If you want to study this concept on the euro, the usual route is the CME euro futures contract, where trades are recorded on one exchange.

A practical reading routine

To use the label as an observation rather than a signal, keep the process mechanical:

1. Confirm one tick per row and 1-tick data storage before reading anything.
2. Pick one timeframe, for example the session high and low on ES, rather than every bar.
3. At each extreme, write down bid volume, ask volume and the label.
4. Note the rows just inside the extreme, so you see whether volume thinned out or stayed heavy approaching the high or low.
5. Later, in replay, record what price actually did afterward, without deciding in advance what it should do.

The routine in how to practice reading order flow charts fits this kind of journaling well. If you would rather start from a footprint that is already built with Numbers Bars, a Sierra Chart footprint chartbook saves the setup time, but still check the row size and data settings above before reading extremes.

Conclusion

An unfinished auction is a narrow, well-defined observation: the high or low row of a footprint shows trades on both the bid and the ask. It is fully determined by two cells, which makes it easy to read and easy to distort through row grouping, coarse data or a mismatched timeframe. Read it for what it is, a record of who traded at the extreme, and keep any theory about later price behavior separate and testable.

FAQ

Is an unfinished auction the same as a poor high or poor low?

They come from the same auction market theory idea of an extreme without clean rejection, but they are usually read differently. Poor highs and lows are often judged on a market profile or TPO shape, while the unfinished auction label is read from bid and ask numbers in a footprint row.

Does a large volume at the extreme make the unfinished auction more important?

The label only requires both sides to be above zero, so 1 x 1 and 300 x 280 receive the same label. Any extra weight you give to size is your own interpretation, which is why it is worth recording the actual numbers rather than just the label.

Can a bar have an unfinished high and a finished low?

Yes. The high and the low are classified independently, so one bar can carry any combination of the two labels.

Why do my historical bars show different labels than they did live?

The usual causes are a change in row size, a reloaded chart with different stored data, or a feed that corrected trades. Check that the data storage unit is still 1 tick and that the row increment matches what you used live.

If you want a footprint workspace ready to open so you can focus on reading the extreme rows, browse the Sierra Chart chartbooks at SierraOnShop.