Understanding what is spread is one of the most important basics in trading. The spread is the difference between the price a buyer is willing to pay and the price a seller is willing to accept. In markets like forex, stocks, futures, and ETFs, this difference is a real trading cost and a key part of how prices are formed. In simple terms, the spread is not extra profit for the trader; it is the cost of getting into and out of a trade.
What Is Spread in Trading?
A spread is the gap between the bid price and the ask price. The bid is the price someone is willing to pay, while the ask is the price someone is willing to sell at. In forex, the SEC explains that the bid is the lower amount you receive when selling a currency, while the ask is the amount you pay when buying it; the difference between them is the bid-ask spread.
In U.S. equity markets, the best bid and offer across exchanges form the National Best Bid and Offer, often called the NBBO. The SEC notes that the difference between the best bid and best offer is the bid-ask spread. That spread is a core indicator of market pricing and liquidity.
Why the Spread Matters
The spread matters because it is part of the cost of trading. When you buy, you usually do so at the ask price, and when you sell, you usually do so at the bid price. That means a trade must move in your favor by at least the spread before it becomes profitable. For active traders, especially those making many short-term trades, even a small spread can have a meaningful effect on results.
This is why traders often compare spreads before choosing a broker or market. A tight spread generally means lower trading costs, while a wide spread means higher trading costs. CME Group describes tight bid/ask spreads as part of what can help lower trading costs in liquid markets.
What Makes a Spread Tight or Wide?
The spread is not fixed in every market. It changes with liquidity, volatility, and trading hours. When there is more trading interest, spreads usually become tighter. When trading interest is lower, spreads can widen. The SEC notes that reduced trading interest, such as in after-hours trading, generally results in wider spreads between bid and ask prices. OANDA also notes that spreads typically widen around market close and market open because liquidity is lower at those times.
Market volatility can also affect spreads. When prices move quickly, brokers and market makers may widen spreads to manage risk. That is why major news events, thin trading periods, and market stress often lead to a wider broker spread or forex spread.
Spread in Forex Trading
In forex, the spread is one of the main transaction costs. The SEC’s forex investor alert explains that currency prices are quoted with a bid and an ask, and the difference between them is the bid-ask spread, which is an inherent cost of trading. OANDA gives the same basic definition and notes that the spread is the difference between the ask and bid price.
For traders, this means that a currency pair with a smaller spread is usually cheaper to trade. That is why major currency pairs often attract more attention: they tend to have higher liquidity, and higher liquidity often supports tighter spreads. CME Group similarly highlights tight bid/ask spreads as part of the trading cost advantage in highly liquid FX markets.
Spread and Liquidity
Spread and liquidity are closely linked. Liquidity refers to how easily an asset can be bought or sold without causing a large price change. In more liquid markets, buyers and sellers are easier to match, so the spread is usually smaller. In less liquid markets, there may be fewer orders available, so the spread often becomes wider. CME’s liquidity tool is specifically designed to analyze bid-ask spread, book depth, and cost-to-trade data because those measures help describe how liquid a market is.
This is one reason why spreads are often used as a quick market-quality signal. A tight spread usually suggests active participation and smoother execution. A wide spread often suggests lower liquidity, higher uncertainty, or both.
Simple Example of a Spread
Suppose a market shows a bid price of 1.1000 and an ask price of 1.1002. The spread is 2 pips. If a trader buys at 1.1002, the price must rise above that level before the trader can show a profit. That is the basic effect of spread cost.
This example is simple, but it shows the practical point: the spread is the first hurdle a trade must overcome. The smaller the spread, the easier it is for a trade to move into profit.
Tight Spread vs Wide Spread
A tight spread is usually better for traders because it reduces entry and exit cost. A wide spread makes a trade more expensive and can hurt short-term strategies such as scalping or very frequent trading. Wider spreads are more likely during low-liquidity periods, around market open or close, or when volatility rises sharply.
This is also why traders should not look at price alone. Two markets can show similar prices but very different total trading costs if one has a much tighter spread than the other.
Spread vs Commission
Some brokers charge mainly through the spread, while others use a mix of spread plus commission. In a spread-only model, the broker’s revenue is built into the bid-ask difference. In a commission model, the spread may be lower, but a separate fee is charged per trade. OANDA notes this difference in pricing models for forex trading.
For traders, the important part is the total cost. A low spread is helpful, but the real question is how much the trade costs all-in after spread, commission, and execution quality are considered.
Conclusion
So, what is spread? A spread is the difference between the bid price and the ask price of an asset, and it is one of the most important trading costs. It changes with liquidity, volatility, and market conditions. A tighter spread usually means lower cost, while a wider spread usually means higher cost. Understanding the bid ask spread, forex spread, and how liquidity affects pricing helps traders make better decisions and avoid unnecessary trading costs.