What is Bid-Ask Spread?
The bid-ask spread is the difference between the best bid and best ask. Wider spreads tax market orders and fast entries.
Formula
Bid = highest buyer price; Ask = lowest seller price
Indian market context (NSE)
Reference levels: Nifty 50 at 24,300, Reliance Industries at ₹1,300, Bank Nifty futures at 55,000 (lot size 30). Examples below show how Bid-Ask Spread shows up on Indian index, equity, and futures books — update to live quotes in your journal.
Nifty 50 perspective
Bid-Ask Spread on NSE cash and Nifty (24,300): co-movement with global futures (SGX/GIFT) affects open print — log pre-market cue in journal.
Bank Nifty futures perspective
Bid-Ask Spread visible in Bank Nifty depth at 55,000: banking basket drives ~40% of index move; watch HDFC/ICICI/Kotak contribution when interpreting bid-ask spread.
How to validate
- Validate Bid-Ask Spread separately for index weeklies vs stock options.
- Stress-test with expiry-week and event-week subsets (RBI, budget, results).
- Confirm margin and tail-loss scenarios are logged for short premium books.
- Discard readings polluted by untagged discretionary adjustments.
How to track in TradeLyser
- Tag every leg: structure, DTE, moneyness, and whether Bid-Ask Spread was a primary driver.
- Log planned max loss ₹ on entry for short premium strategies.
- Weekly: list open short ITM/ATM legs before expiry with a written roll/close rule.
- Separate F&O account tags from cash equity for Bid-Ask Spread statistics.
Best practices
- Size Bid-Ask Spread trades with margin headroom for gaps and assignment.
- Prefer defined-risk structures when learning a new options concept.
- Roll or close based on written DTE rules, not convenience.
- Keep weekly index and monthly stock books in separate tags.
Common pitfalls
- Short premium without defined max loss while Bid-Ask Spread risk builds.
- Holding illiquid stock options into expiry without a plan.
- Blending index and stock gamma exposure in one tag.
- Ignoring margin spikes on gap opens.
How to use this in TradeLyser
Record spread or % of price on entry. Filter analytics: wide-spread vs tight-spread symbols.
Related terms
A limit order sets the worst price you accept. Buy limits fill at or below your price; sell limits fill at or above.
Liquidity describes depth and ease of entering/exiting at stable prices. Nifty top names differ sharply from illiquid small caps.
A market order matches the best available liquidity now. You accept slippage in exchange for certainty of fill.
Slippage is the difference between the price you intended and the price you received. It rises in fast markets and thin books.
FAQ
What is bid-ask spread in simple terms?
The bid is what buyers offer; the ask is what sellers want. The gap between them is the spread. If bid is ₹99 and ask is ₹100, the spread is ₹1. You buy at ask, sell at bid—so you start every trade down by the spread.
Why does bid-ask spread matter?
Spread is a hidden trading cost. Wide spreads mean you pay more to enter and receive less when exiting. Active traders in liquid stocks minimize spread costs; illiquid stocks have expensive spreads.
What is a good bid-ask spread?
Tighter is better. For liquid large-caps, spreads of 0.01-0.05% are normal. Mid-caps might have 0.1-0.5% spreads. Small-caps can have 1%+ spreads. Spreads widen during volatility and narrow during calm.
How do market makers profit from spreads?
Market makers buy at bid and sell at ask, pocketing the spread. If they buy 1,000 shares at ₹99 and sell at ₹100, they make ₹1,000. They provide liquidity and earn the spread as compensation.
Does bid-ask spread change?
Yes, constantly. Spreads narrow when liquidity is high (more buyers/sellers) and widen when liquidity is low or volatility spikes. Opening minutes and news events typically have wider spreads.
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