Definition
A market order is an instruction to buy or sell immediately against the best prices currently available in the order book.
The price is discovered during execution
A market order prioritizes completing the trade. It matches the best available opposing orders, but the displayed quote is not a guaranteed execution price. Prices can change before the order reaches the book, and a large order may consume liquidity at several price levels.
The difference between the expected price and the average fill price is slippage. Thin liquidity, wide spreads, large order size and fast markets can increase it. Some venues reject market orders that would exceed a configured slippage limit.
Immediate does not always mean complete
A venue can fill a market order in several trades, fill only the available quantity or reject it under its execution rules. The final trade result is the evidence of execution, not the quote shown before submission.
What it does not mean
A market order prioritizes speed and accepts available prices. A limit order prioritizes a price boundary and may never fill.
Where this term fits
Questions about market order
- Does a market order guarantee the displayed price?
- No. It matches available liquidity, so the final price can differ from the quote visible before submission.
- Why can one market order have several fill prices?
- The requested quantity can consume multiple order-book levels when one price does not contain enough liquidity.
- Is a market order always fully filled?
- No. Venue rules, liquidity and slippage controls can produce partial fills or rejection.
See these concepts in context
Review the Fensory MCP connection, tools and account controls.