Order book and spread

🧭 Background & Context The order book is the electronic heart of every exchange: it lists all open buy and sell orders for a security by price and quantity. The spread is the difference between the best bid price and the best ask price – that is, the highest price a buyer is willing to pay and the lowest price a seller will accept. From an economic perspective, the spread is a direct component of transaction costs: the tighter it is, the more liquid and efficient the market, while a wide spread indicates thin trading and higher risks. For private investors, the order book is primarily a barometer of sentiment and liquidity. A deep order book with many levels signals that large orders can be executed without significant price disruptions – this reduces the risk of slippage. The spread, in turn, directly determines the profitability of short-term trades: anyone buying at a spread of 0.5 percent must already achieve a price gain of half a percentage point just to cover the costs. Therefore, investors should never place orders blindly at the market price, but rather use limit orders to actively control the spread. The importance ultimately lies in cost transparency: those who read the order book and spread can recognize whether a price is „fair“ 🔍 How It Works in Detail The order book is like a continuously updated list of all buy and sell orders for a specific security. On one side are the bids at which buyers are willing to pay, on the other are the asks at which sellers want to sell. The spread is simply the difference between the highest bid and the lowest ask – that is, the gap between the best buy and sell price. A narrow spread means that buyers and sellers are close together, which indicates a liquid market, while a wide spread points to low trading activity or high risk. When you place an order, it is added to this book and only executed when a counterparty is willing to trade at your price or better. The spread is simu …