What is iceberg order?

A large order that shows only a small slice on the public order book and refills that slice automatically as it fills.

The point is to work size without advertising it, since a visible large bid or offer invites other traders to trade ahead of it or pull away from it. Exchanges that support icebergs let you set the visible quantity and the total, and they generally treat each refill as a new order for queue priority.

Not every venue offers them, and futures and spot markets on the same exchange may differ. For most retail buyers the term is worth knowing less as a tool to use than as an explanation for something you can observe: a price level that keeps absorbing sell pressure without the displayed size ever changing.

How it works

You submit one order with two quantities: the total you want to trade and the slice you are willing to display. The matching engine posts the slice at your limit price and keeps the remainder hidden in its own records. When the visible slice fills, the engine posts another slice of the same size, and so on until the total is exhausted or you cancel.

Queue priority is the cost. On most venues each refill enters the queue at the back of its price level, behind every order already resting there. A plain order of the same total size would hold one place in the queue and fill straight through. An iceberg gives up that continuity in exchange for concealment, which is why it executes more slowly at the same price.

Concealment is also partial. A counterparty watching the tape can see that trades keep printing at a level whose displayed size never falls, and infer a hidden seller or buyer. Some venues charge differently for hidden liquidity or exclude it from maker rebates, and some publish the visible portion only in their market data feed. The order documentation for the specific venue and market is the authority on all of this.

Example

Illustrative arithmetic. You want to buy 50 BTC at $60,000 and set a display size of 2 BTC. The book shows a 2 BTC bid at $60,000. A seller hits it, and the display refreshes to 2 BTC again. After 25 such fills your order is complete. Anyone reading the book saw a 2 BTC bid the whole time, never a 50 BTC bid, so the price level did not repel sellers the way a visible 50 BTC wall might have. The tradeoff: each of those 25 slices waited behind whatever else was resting at $60,000, so the order took longer than a single 50 BTC bid would have.

Why it matters when you buy

Retail-sized orders do not need this, but the reason icebergs exist is the reason your own large order can move a price: a book only holds so much size near the top. The liquidity view shows the notional resting within one percent of the mid and the slippage a $500, $5,000, or $50,000 market buy would pay on each venue we measure. If your order is large relative to that depth, splitting it over time does the same job an iceberg does.

Related terms

• order book: the display an iceberg hides size within
• limit order: the order type it attaches to
• market depth: how much size sits near the top
• slippage: the cost of trading through thin depth
• twap: another way to work size over time
• front running: the behavior concealment defends against

Questions

Can I tell if a level is an iceberg?

Not for certain. A level that keeps refilling at the same displayed size after repeated trades is the usual tell, but a series of separate traders can produce the same pattern.

Do all exchanges support them?

No. Support varies by venue and by market within a venue, and the display size is often subject to a minimum. Check the order type documentation for the market you trade.

Is an iceberg cheaper than a market order?

It rests on the book, so it pays the maker side of the fee schedule rather than crossing the spread. It also may not fill at all if the price moves away.