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 buy limit places a maximum acceptable execution price. It may receive that price or a better one, but it can remain unfilled. Eligibility and queue allocation are different questions; actual priority rules depend on the venue and order type.
Guided example · Simplified frozen FIFO queue · not an exchange reconstruction
A touch does not tell you your fill
Use an explicitly simplified FIFO queue at one fixed limit price.
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.
Use an explicitly simplified first-in, first-out queue. Five units at 100.00 are ahead of your two-unit buy order. This is a teaching model, not a description of every exchange.
When six sell units transact at 100.00 under the frozen FIFO assumption, allocate five to earlier orders and one to your two-unit order.
Define an order expiry and what you do with an unfilled remainder. Cancelling or changing an order can affect priority under the applicable rules.
The quoted rules are illustrative research specifications. Parameters are not recommendations and have not been presented as profitable backtest results.
What can this cost?
A partial position has different exposure from the requested quantity. Check linked protective orders and do not assume they automatically adjust correctly.
How the idea can fail.
A backtest that marks every limit-price touch as a complete fill ignores priority and available volume. Its apparent precision can be unavailable in live trading.
Practical habit
Record requested quantity, filled quantity, average price and remaining quantity separately.
Go one level deeper
Include an explicit fill policy and sensitivity analysis. A last-trade chart may not reveal whether the required sell-side price was available.
Check your understanding
Five FIFO units are ahead of your two units. Six sell units trade at the limit. What reaches your order?
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