What is a market order?

An order to buy or sell immediately at the best available prices in the order book.

A market order takes liquidity from the order book: it fills against existing limit orders right away. You get speed but not a guaranteed price — a large order eats through several levels and suffers slippage.

Large market orders show urgency: someone is ready to overpay to get in or out right now. That is why they are watched more closely than limit orders.

On HyperScan

HyperScan collects market orders of $1M and more and flags as anomalous those of 1.5% or more of the coin’s daily volume.