An orderbook is a list with all the passive buy and sell orders for a specific market.
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The example above is an FTX orderbook for the BTC/USD perpetual swap contract.
Let's dissect every aspect of the orderbook.
First of all it's important to understand that an orderbook only shows what is called "passive orders", also known as "limit orders". These are orders that people set at a price they're hoping to get and then those orders rest at that price level until it gets filled by "active orders" which are more commonly known as "market orders". It's also possible that price simply refuses to move to your passive orders and then your orders simply never get filled. Usually limit orders come with lower fees than market orders because you're adding liquidity to the orderbook instead of taking liquidity away. That's why limit orders are also referred to as "maker" and market orders as "taker".
The orderbook allows us to see how many orders there are resting at each given price level. That means it also shows how much liquidity there is. Liquidity isn't always what it seems though. Oftentimes there are market participants playing mind games and they'll pull (cancel) orders right before they get a chance to get filled. This phenomenon is called "spoofing" which is a common trick to move price into a certain direction. With experience a lot of spoofing can be quite easily detected because that type of activity is often very recognizable. More on this later.
In the example of the FTX orderbook you can see that the size of the orders is denominated in BTC, they could also be denominated in USD (or a USD variant, like USDT for example). In white text it shows level per level the total size of all the orders resting at those levels. The green and red visualizer represents the cumulative order volume which simply means all of the orders up to that price level added up.
The FTX orderbook shows the buys and sells side by side, but orderbooks can also be displayed in stacked format like in the example below.
On an advanced orderbook website like Okotoki you can get an overview of all the orderbooks of the most prominent exchanges for any market you're interested in (example above). You can group the orderbook by any dollar amount. Grouping means that each price level jumps by the chosen increment and it aggregates the orders between each level. Grouping is recommended otherwise you'll only see a very small section of the orderbook. However if you're scalp trading on low timeframes then you most likely won't need to look very deep into the OB.
Let's make sure that you can correctly read the chart above.
At the top you can see the exchanges and markets. On the left of each orderbook you can see the price and on the right the total order size per level denominated in BTC typically for spot markets and linear perpetual swaps, while inverse perpetual swaps tend to be denominated in USD.
The squares in between with different kinds of white shading visually reflect how big the order size is at each given level. The brighter the square the bigger the size relative to the rest of the orders in that orderbook.
In the middle it shows the last price of the asset selected. The top side of the orderbook (the part above the last price) is the ask side (side with all the limit sells), the bottom part is the bid side (side with all the limit buys).
The green or grey number next to the last price in the middle of the screen is the "delta" or the difference in size between all buys and sells. In the settings you have to choose how deep you want the tool to look into the orderbook to calculate this delta. If the number is green it means the bid side is thicker, vice verse if it's grey the ask side is thicker. It's an easy way to visualize whether the demand or supply side is stronger.
Finally you'll see the trades delta at the bottom. It shows per 5m, 30m and 1h how much market buying or selling happened on each given market.
Some of the features just discussed are unique to Okotoki though. This application is free to use but there's also a paid version with extra features. If you're interested, consider using my referral link for a 20% discount: https://okotoki.com/byz
A little more info about spoofing.
If you're actively watching the orderbook in real time you can spot spoofing. When someone's spoofing you'll see typically large orders appear and disappear over and over again. They tend to "follow" price closely although they're not meant to follow price, they're meant to "push" price into a desired direction. Spoof orders will always disappear right before price has a chance to hit it. Orders that are placed further away from last price and have been static for a while are much less likely to be spoofs. - It's possible that spoofs accidently get filled when someone's doing it manually. -
When you see spoofing happening it's probably best to not trade against the direction of the spoofer(s) until they're done. The most straight forward type of spoofing happens when someone with deep pockets wants to fill a large order but they have to engineer some liquidity to make it happen. For example when someone wants to fill longs they'll put up big asks pushing price down, possibly triggering stop-loss orders too, in the hope that it fills their bids.
Supply and demand
Orderbooks aren't just useful to figure out how liquid a market is, it can also give valuable insight into where supply and demand levels are located. Most traders use some form of technical analysis, but once you've highlighted price levels that seems important it could be useful to check the orderbooks of the highest volume markets for confirmation that there are actually orders sitting there (or not).
The dominant orderflow and most impactful one is the active flow (market buying and selling). That's the flow that guides us, but it hits passive resistance in both directions. This passive resistance is what you can observe in the orderbook.
You'll notice that often times the bulk of the orders is sitting at the same price level across multiple exchanges at the same time, the chart above is a perfect example. The last price in this example was around $19000. I scrolled down a little bit into the orderbook to see where the passive demand was sitting and I noticed that on most exchanges there were a lot of resting orders at $18000.
In this case you can reasonably assume that 18k will in fact be support because these probably aren't spoofs since they've been resting there for a bit, they're pretty far away from the last price and we can observe similar activity on a bunch of different exchanges. Because there are a lot of orders sitting there we know that people are looking at that level to buy, so if price were to dip to 18k there would probably be a bunch of market participants that start market buying as well. The passive orders aren't the full story, they're an indication of which levels people are looking at to buy or sell (or take profit / put stops).
Orderbooks can also be observed in the form of "heatmaps".
This might look terribly complex and weird but it's actually fairly easy to read.
But that'll be for the next post!