What are a buy wall and a sell wall?
In short
A buy wall is a large concentration of buy orders at one price level in an exchange’s order book. A sell wall is the equivalent “wall” of sell orders.
Imagine a market where lots of people are waiting to buy the same product at €9, while others have lined up large quantities for sale at €11. In crypto, these concentrations show up in the order book: the buy wall and the sell wall.
Walls are made up of pending limit orders, either one large order or many smaller ones. They count as large relative to the other orders in that particular market, not according to some fixed amount. On a depth chart, which shows cumulative buy and sell quantities, they often look like steep steps.
In a hypothetical example, a token is trading around €10 and there are buy orders for 100,000 tokens at €9, far more than at the neighboring levels. That’s a buy wall. If the market gets there, sellers can trade against these orders. A sell wall works the other way around: buyers absorb the quantities available for sale.
Why it matters
A buy wall can act as temporary support and a sell wall as resistance. For the price to move past their level, those orders have to be filled or pulled. A wall doesn’t guarantee the price will stop there.
For us, their usefulness is that they show where visible supply and demand is concentrated at that moment. But they apply to a specific exchange and trading pair, not to a coin’s entire market.
What to watch out for
Pending orders are not completed trades. A large wall can be canceled or moved before it’s filled. Sometimes large orders are placed with no intention of being executed, to create a misleading picture of supply or demand, a practice known as spoofing. That said, canceling an order doesn’t on its own prove manipulation.
From a snapshot, you also can’t tell whether there’s one large holder behind the wall or many different users. That’s why its size alone isn’t enough to draw conclusions about the price’s next move.