What is the bid-ask spread?

The bid-ask spread is a fundamental concept in capital markets that reflects market liquidity and transaction costs. The bid price is the highest price a buyer (or market maker/specialist) is willing to pay for a security, while the ask price is the lowest price at which a seller is willing to sell. The difference between these two prices is the bid-ask spread. From a financial management perspective, the spread compensates market makers for providing liquidity, bearing inventory risk, and facilitating continuous trading. A narrow bid-ask spread generally indicates a highly liquid security with strong trading volume and low transaction costs, while a wide spread suggests lower liquidity, higher risk, or limited information availability. Investors effectively pay the spread when buying or selling securities, making it an implicit cost of trading. This concept is critical when evaluating market efficiency, trading strategies, and execution costs, especially for large institutional trades. Option D correctly defines the bid-ask spread as the difference between buying and selling prices quoted by specialists or dealers.