Understanding Bid-Ask Spreads

Learn about the hidden cost of trading and how spreads impact every transaction

Last updated: 6/24/2025

In financial markets, the "spread" refers to the difference between the highest price a buyer is willing to pay for an asset (the "bid") and the lowest price a seller is willing to accept (the "ask"). The bid-ask spread represents an implicit cost of trading that every investor should understand.

Bid and Ask Prices Explained

Bid Price

The highest price that buyers are willing to pay for an asset right now. This is the price you receive when selling.

Key Characteristics:

  • Always lower than the ask price
  • Represents buyer demand
  • Changes with market activity
  • Price you get when selling

Ask Price

The lowest price that sellers are willing to accept for an asset right now. This is the price you pay when buying.

Key Characteristics:

  • Always higher than the bid price
  • Represents seller supply
  • Updates in real-time
  • Price you pay when buying

Example: Apple (AAPL) Stock

Apple Inc. (AAPL)

BID
$174.50
Price you can sell at
ASK
$174.55
Price you can buy at
Spread = $174.55 - $174.50 = $0.05
This is your trading cost

How Spreads Impact Your Trading

Transaction Cost

The spread represents an immediate cost every time you trade. Market makers earn this difference for providing liquidity.

Immediate Impact

When you buy, you're instantly "down" by the spread amount. Your position must move favorably to overcome this cost.

Liquidity Indicator

Tighter spreads indicate higher liquidity. Wider spreads suggest lower liquidity and higher trading costs.

Real Trading Scenario

Buying 100 Shares of AAPL

Purchase price (ask):$174.55
Immediate sell price (bid):$174.50
Immediate loss per share:-$0.05
Total immediate loss:-$5.00

Spread by Asset Type

Large-cap stocks$0.01-0.05
Small-cap stocks$0.05-0.25
Penny stocks$0.25+

Managing Spread Costs

Smart Trading Practices

  • Trade during market hours for tighter spreads
  • Focus on high-volume, liquid assets
  • Use limit orders instead of market orders
  • Consider spread costs in your strategy

When Spreads Widen

  • Pre-market and after-hours trading
  • During major news announcements
  • Market volatility spikes
  • Low trading volume periods