™A market buy for 200 shares can consume a $50 offer for 100 and a $50.10 offer for another 100; priority of execution does not guarantee one price.
Orders & Market Structure
Market order
An order seeking prompt execution at the best available prices; the execution price is not guaranteed.
Plain-English context
Put the definition to work.
Execution priority does not assure one price, immediate execution during a halt or unlimited available liquidity.
Further reading and verification. Examples are hypothetical, not current quotes or recommendations. Product terms, tax treatment and market rules can change. FINRA — order types and execution