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Key Takeaways
- A market maker regularly quotes buy and sell prices for its own account.
- Its executions create inventory that the firm prices, hedges and manages.
- The worked matched cycle buys and sells 300 shares for $12 of gross spread capture.
- Exchange appointments define the securities and quoting obligations attached to each role.
- Compare spread, size and completed fills when selecting a contract and order price.
What is a market maker?
A market maker is a dealer or registered exchange participant that regularly stands ready to buy and sell designated securities for its own account. Its bid is the price at which it buys; its offer is the price at which it sells. Executions change its inventory, which the firm manages through pricing and hedging.
Market makers quote alongside customer limit orders, other dealers and trading firms. Exchange registration and appointments define each market maker’s role and obligations.
How market makers earn the bid-ask spread
The worked dealer quotes 500 shares at $49.98 bid and $50.02 offer. It buys 300 shares at the bid and sells those 300 at the offer.
The four-cent price difference multiplied by 300 shares produces $12 of gross spread capture. Net inventory from the completed cycle is zero. If only 100 shares sell, the remaining 200 belong in the open-inventory calculation.
Separate matched spread capture from the complete trading result. Add fees, rebates, hedge transactions and changes in remaining inventory to reconcile the firm’s position.
Formula
Gross spread capture = matched shares × (average sale price − average purchase price)- Matched shares are quantities bought and later sold without leaving net inventory in the simplified calculation.
- Fees, rebates, hedging costs, price movement, and unmatched inventory change the actual result.
Worked Example
A market maker quotes 500 shares of XYZ at a $49.98 bid and a $50.02 offer. It buys 300 shares at the bid and later sells those 300 shares at the offer.
- Quoted spread: $50.02 − $49.98 = $0.04 per share
- Matched quantity: min(300 bought, 300 sold) = 300 shares
- Gross spread capture: 300 × $0.04 = $12.00
- Net inventory after both trades: 300 − 300 = 0 shares
The simplified matched cycle earns $12 before fees, rebates, hedging, and price risk. If the market maker had sold only 100 shares, it would still own 200 shares and remain exposed to the next price move.
Market maker obligations
Exchange rules attach quoting obligations to registered securities or appointed option classes. NYSE Arca’s market-making framework includes continuous two-sided displayed quotes during Core Trading Hours for registered securities. Options venues define class appointments and requirements for their market-maker categories.
For a trader choosing an options contract, the spread, available size and completed executions at the selected strike and expiration show what the contract costs to trade, and options flow shows the activity across the contracts under consideration.
Market maker vs broker
A broker acts as agent when executing for another person. A market maker acts as principal when trading for its own account. A broker-dealer can use both capacities in separate transactions.
Limitations of market maker quotes
- Size the order against the quoted size. The worked market maker quotes 500 shares on each side, so a larger order reaches other dealers and customer limit orders at the next prices.
- Check the venue’s market-maker rules for the security or class. Exchange rules set quoting times, sizes and widths for registered securities or appointed classes, and a fill beyond the quoted size depends on who else is quoting.
- Reconcile the $12 gross spread capture with fees, rebates, hedge transactions and changes in remaining inventory to get the firm’s actual result.
- Count unmatched inventory as open price risk. Selling only 100 of the 300 shares would leave 200 exposed to the next price move.
Bottom line
A market maker supplies two-sided quotes for its own account and earns the spread, before fees, rebates and hedging, when it can buy and sell without carrying inventory into a price move. Read its quote for both price and size, compare the spread with completed fills, and expect a larger order to reach prices beyond the inside quote.
Clear answers
Frequently Asked Questions
Sources and Further Reading
- SEC: Rule 605 FAQ and Market Maker Definitions
- NYSE Arca: Market Making
- Cboe Options: Liquidity Provider Programs
How entries are sourced, calculated and updated: editorial methodology.