Bid-Ask Spread Explained: How It Costs You Money
The bid-ask spread is the most pervasive hidden cost in trading. Learn how spreads work, why they exist, and how to minimize their impact on your returns.
Key Takeaways
- ✓The bid-ask spread is the difference between the highest buy price and lowest sell price in the market — every trade crosses this spread.
- ✓Spreads are tighter in liquid markets and wider during volatility or for less-traded securities.
- ✓A stock with a $0.01 spread may seem cheap, but high-frequency traders and large positions amplify the cost significantly.
- ✓To minimize spread costs, trade during market hours, focus on liquid securities, and use limit orders instead of market orders.
Every time you execute a trade, you pay the spread — whether you realize it or not. The bid-ask spread is the gap between the highest price a buyer is willing to pay (the bid) and the lowest price a seller is willing to accept (the ask). This spread represents the immediate cost of entering or exiting a position, and it is one of the most underestimated costs in retail trading.
How the Spread Works
Imagine you want to buy shares of Company XYZ. The current market data shows a bid of $50.00 and an ask of $50.03. The spread is $0.03. If you place a market buy order, you will pay $50.03 per share. If you then immediately sell with a market sell order, you will receive $50.00 per share. In this hypothetical instant round-trip, you have paid $0.03 per share in spread costs — even though you never saw a commission on your statement.
This spread is how market makers and liquidity providers earn their profit. They continuously post both bid and ask prices, providing liquidity to the market, and capture the difference as compensation for the risk of holding inventory.
What Determines Spread Width
- •Liquidity — stocks with high trading volume (Apple, Microsoft) typically have spreads of $0.01. Low-volume penny stocks may have spreads of $0.05 or more.
- •Market hours — spreads tend to widen during pre-market and after-hours sessions when fewer participants are active.
- •Volatility — during high-volatility events (earnings reports, Fed announcements), market makers widen spreads to compensate for increased risk.
- •Order book depth — the number of orders at each price level affects how easily large orders can be filled without moving the price.
- •Asset class — forex major pairs have extremely tight spreads (0.1-1.5 pips), while exotic pairs and small-cap stocks have much wider spreads.
Spread Costs Across Asset Classes
| Asset | Typical Spread | Cost on $10,000 Trade | Notes |
|---|---|---|---|
| Large-cap US stock (AAPL) | $0.01 | ~$2 | Extremely liquid, tight spread |
| Mid-cap US stock | $0.03-$0.05 | $6-$10 | Moderately liquid |
| Small-cap / penny stock | $0.05-$0.50+ | $10-$100+ | Wide and variable spreads |
| EUR/USD (forex) | 0.1-1.5 pips | $1-$15 | Tightest forex spreads |
| Cryptocurrency (BTC/USD) | 0.1%-0.5% | $10-$50 | Varies by exchange and liquidity |
How to Minimize Spread Costs
- •Use limit orders instead of market orders — a limit order lets you specify the maximum price you are willing to pay, potentially improving your fill price.
- •Trade during regular market hours — spreads are tightest when the most participants are active.
- •Focus on liquid securities — trade stocks and ETFs with high average daily volume.
- •Avoid trading immediately after market open — the first 15-30 minutes often see wider spreads as the market digests overnight orders.
- •Consider the spread before trading low-cap stocks — a stock might appear cheap, but wide spreads can make entry and exit expensive.