The short answer
A displayed market price is information, not an execution promise. The last trade, the best bid and the best ask describe different things, and the available quantity at a price can be smaller than your order. Prices can also change while an order reaches its execution channel. The individual fill records show what actually executed.
This guide explains direct US equity and crypto spot orders. The platform is invitation-only; account approval, identity checks, instrument availability and market rules still apply. US equities use whole shares by default. A-shares are quote-only, tokenized RWA is not live, and portfolio products follow their separate allocation and redemption rules.
Which price are you comparing?
| Price | What it describes | What it does not promise |
|---|---|---|
| Last trade | The price of a recorded trade. | It does not mean another order can trade at that price now. |
| Best bid | The highest displayed buying price, for the displayed quantity. | It does not mean an entire sell order can fill there. |
| Best ask | The lowest displayed selling price, for the displayed quantity. | It does not mean an entire buy order can fill there. |
Worked example: one quote, more than one price level
All figures below are invented teaching inputs for an unnamed crypto instrument, in quote units per unit of the asset. They are not live quotes, a recommended order or a simulation of a particular platform channel. Assume these offers remain available, no competing order changes them, and fees are excluded.
| Hypothetical sell offer | Available quantity | Used by a hypothetical buy of 3 units |
|---|---|---|
| 100 quote units | 2 units | 2 units at 100 |
| 102 quote units | 2 units | 1 unit at 102 |
Executed value before fees = (2 × 100) + (1 × 102) = 302 Filled quantity = 2 + 1 = 3 Average fill price = 302 ÷ 3 = 100.666… ≈ 100.67
The hypothetical order has an average above the displayed best ask because part of it uses the next price level. In an actual market, offers can move or disappear before execution, so neither this average nor completion of the order is assured.
How the order type changes the question
A market order seeks available execution without a specified limit price; its final price is uncertain. A buy limit order sets the highest execution price permitted, while a sell limit order sets the lowest. A limit order can remain unfilled.
In the same unchanged teaching snapshot, a buy limit of 101 would exclude the offer at 102. The example could fill 2 units at 100 while the remaining unit stays unfilled. This is a contrast between price conditions, not advice to choose a particular order type or limit.
Platform validation, available funds, supported quantities, risk limits and execution-channel availability still apply to both order types. A submitted order or a satisfied conditional trigger does not guarantee a fill. Use the actual order status and fills, rather than a quote, to establish what happened.
Check the record before drawing a conclusion
- Check the symbol, market and quote timestamp, and whether the number is last trade, bid or ask.
- Compare the order type, requested quantity and any limit with each actual fill quantity and price.
- Keep execution price separate from fees and from a position cost or P&L figure. Check the current fee schedule instead of assuming this example includes costs.
- For a partially filled order, calculate the average only over executed quantities. The related average-price guide provides a fill and cancellation timeline.
The official Investor.gov materials below provide general market terminology; they do not verify or endorse the platform. The internal links explain the platform-specific scope and rules. This article is educational and does not recommend an investment or trading strategy.