Microstructure · Core
Market Order
A market order is an instruction to buy or sell now at the best available prices — certainty of fill, uncertainty of price.
Definition
The order sweeps the book until filled. In fast markets it can walk several levels. Some venues convert it to a limit at a collar. You pay the spread and the impact for immediacy.
Why it matters
Retail and distressed hedging use it. Professional flow uses limits and algos because a market order is a gift to whoever is quoting.
Case
A halt resume opens with a market-on-open imbalance. Market orders become the imbalance; the print is a gap, not a tick.
How to read it
If you needed the fill more than the price, say so. Otherwise a limit or a POV algo is the adult version of the same intent.
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