The lesson on YouTube
Watch. Then work through the idea.
Watch the English lesson first, then use the worked example and quiz below to check the idea. The article is a companion, not a transcript.
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What is actually happening?
A market order seeks execution against available opposite-side liquidity under the venue’s rules. If the first price contains less quantity than your order, additional pieces may trade at other prices. The full order has an average fill, not necessarily one execution price.
Guided example · Frozen synthetic ask ladder · available quantities assumed
Follow three units through the asks
Allocate the order from the cheapest available ask upward.
Restart & example assumptions
Authored synthetic observations, shown in sequence. Every comparison uses only the revealed data. This is a worked learning example, not live prices, broker execution or a profitability backtest. Follow the article’s exact definitions; measurements and pattern names alone do not authorize a trade.
For charts: tap a candle or swing to inspect it; drag horizontally to browse; wheel or +/− to zoom; arrow keys to inspect; Home to restore the step view.
Make the conditions explicit.
This exercise freezes a synthetic order book and assumes all shown units remain available. Real quotes can be cancelled, added or repriced while an order travels.
For the exercise, buy three units against one unit offered at 100.00, one at 100.10 and three at 100.20. Allocate the order from the cheapest available ask upward.
Do not report a full three-unit fill if the execution report shows a rejection or partial fill. A chart or a prior quote is not a substitute for the report.
The quoted rules are illustrative research specifications. Parameters are not recommendations and have not been presented as profitable backtest results.
What can this cost?
Execution priority is not a guarantee of a specific price, time or quantity. Gaps, venue protections and order rejection rules matter.
How the idea can fail.
Sizing the trade using the best ask of 100.00 can understate risk if the actual average entry is 100.10 and the stop remains unchanged.
Practical habit
Recalculate exposure from the actual average entry after execution. Keep every partial fill in the record.
Go one level deeper
Compare the order quantity with the quoted quantity at relevant prices, while acknowledging that displayed depth is neither all liquidity nor executed volume.
Check your understanding
One unit fills at 20.00 and three fill at 20.20. What is the average fill?
Further reading & boundaries
These examples are original educational exercises. General background: CME Group: position sizing; Fidelity: technical analysis. Neither endorses these example rules. No hypothetical result establishes future profitability.
Editorial revision: 13 October 2026 · Synthetic data · Educational use