Over the shortest horizons, price discovery is largely a story about queues. Price moves when the queue at the best level is exhausted, and how quickly that happens depends both on the rate of aggressive orders and on how fast liquidity is replenished.
01Depletion and replenishment
A level can be depleted by trading or by cancellation, and the two mean different things. Trading reflects demand meeting supply; cancellation reflects liquidity providers changing their minds. Replenishment, the arrival of new orders at or near the best price, determines whether a depleted level is quickly rebuilt or left thin.
02Queue dynamics
Queue position matters to those providing liquidity. Orders at the front are filled first; orders at the back tend to be filled only when the level is about to be exhausted, which is often just before price moves against them. This asymmetry shapes behaviour as a queue shrinks: the closer a level is to depletion, the more likely its remaining orders are to cancel.
A thinning queue often accelerates its own depletion.
03Implications for price discovery
When replenishment is fast, aggressive flow is absorbed and price discovery is gradual. When it is slow, or when cancellations rise as a level thins, price can move several ticks on modest volume. Short-term volatility is therefore partly a property of the replenishment process, not only of the information arriving.
Studying these dynamics requires full-depth, time-stamped order book data. Top-of-book snapshots hide most of what matters.
Insights are research notes published for general information and education. They describe market mechanisms, not the firm’s positions or results. They are not investment advice or research recommendations, and nothing in them is an offer or solicitation.