Bid-Ask Prices and Spreads

Bid-ask prices and spreads covers quote terms for ask price, bid price, bid-ask spread, and spread interpretation.

Use this branch when the issue is what side of the market a quote represents and what the spread says about transaction cost or liquidity. This content is educational and does not state that a quoted price is fair.

What This Branch Covers

Decision Lens

The bid and ask are sides of a quote, not full trade evidence. A spread can indicate transaction cost, but the actual result also depends on size, order type, venue, and market conditions.

Move to Quote Size and Levels when the issue is depth or displayed quantity. Move to Liquidity, Depth, and Transaction Costs when the issue is realized execution cost.

Evaluation Checklist

• Identify whether the number is bid, ask, last sale, midpoint, or indicative.
• Check quote size, venue, timestamp, delay, and quote condition.
• Compare spread with typical spread, volatility, and order size.
• Confirm whether the quote is consolidated or venue-specific.
• Use execution reports to compare quoted spread with actual fill cost.

Common Mistakes

• Treating ask price as the same thing as last sale.
• Ignoring quote size when reading a narrow spread.
• Comparing spreads across sessions without matching liquidity.
• Treating midpoint as an executable price.
• Using the word “spread” without specifying the inputs.

For broader context, return to Quote Levels, Bid-Ask Terms, and Spreads.

In this section

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