What are order book walls? Learn

The order book in one minute

The order book lists every resting limit order on a market: bids (orders to buy below the current price) and asks (orders to sell above it). Each price level shows how much is waiting there. Market orders trade against these levels, so the book shows where liquidity sits before the price gets there.

What a wall is

A wall is a single price level with far more size than the levels around it. A bid wall below the price is a large buy order — it can act as support, because the price has to chew through it to go lower. An ask wall above the price is a large sell order and can act as resistance.

Size alone is not enough. A useful wall is large compared with the rest of the book on the same side, close to the current price, and it stays in place — orders that appear and vanish within seconds are usually algorithms adjusting quotes, not real intentions.

How to read walls

• Price approaches and the wall holds. The level is defended; bounces from it are common while it stays.
• The wall is eaten. Its size shrinks as market orders fill against it. When a large wall is absorbed, the price often moves quickly through the level.
• The wall is pulled. It disappears just before the price reaches it. That is a warning that it may never have been meant to fill.
• Bid / ask balance. Comparing all bids with all asks within ±1% of the price shows which side has more resting liquidity nearby.

Spoofing and other limits

Placing large orders with no intention to fill them, to push other traders one way, is called spoofing. It is prohibited in regulated markets but still appears in crypto. That is the main limit of order book data: a limit order can be cancelled at any moment, so a wall is an intention, not a trade. Order books also show only one venue, and a wall on one exchange can be offset by orders elsewhere. Treat walls as information about where liquidity sits right now — and watch what happens when the price gets there.