Market Makers: The Engines of Liquidity
Market makers are financial firms that stand ready to buy and sell securities at publicly quoted prices. Citadel Securities alone executes approximately 25% of all US retail stock trades. They profit from the bid-ask spread — typically $0.01 to $0.05 per share on liquid stocks.
Market makers perform an essential function: they provide liquidity. Without market makers, there would be gaps in trading — you might wait minutes or hours for a buyer when you want to sell. Market makers continuously quote bid prices (what they will pay to buy) and ask prices (what they will accept to sell). By always being available to trade, they ensure that investors can execute orders immediately at a known price. The difference between the bid and ask — the spread — is the market maker's compensation for providing this service and for taking the risk of holding inventory.
Market makers manage significant risk. When a market maker buys shares from a seller, they hold an inventory position that can lose value if the price falls. To manage this risk, market makers hedge (e.g., shorting futures against long stock positions), limit position sizes, and adjust quotes based on order flow and market conditions. During times of high volatility, market makers widen their spreads to compensate for increased risk. During the 2020 COVID crash, spreads on some stocks widened from $0.01 to $0.50 or more as market makers reduced their risk exposure. This is not greed — it is risk management. A market maker that keeps tight spreads during a crash can be wiped out by adverse price moves.
Real-world example: Citadel Securities is the largest retail market maker, executing about 25% of all US retail trades. When a Robinhood user places a market order to buy Apple, Robinhood typically routes the order to Citadel Securities rather than to the exchange. Citadel executes the trade from its own inventory and pays Robinhood for the order flow (about $0.002 per share). This payment for order flow (PFOF) model allows Robinhood to offer commission-free trading. Critics argue PFOF creates conflicts of interest: brokers route orders to the highest-paying market maker rather than the one offering the best price for the customer.
Designated vs. Electronic Market Makers
On the NYSE, designated market makers (DMMs) are human traders assigned to specific stocks. They have obligations to maintain fair and orderly markets — they must step in to buy or sell when there is a temporary imbalance. DMMs add a human element to trading, using judgment to manage auctions and handle complex situations. On the Nasdaq, electronic market makers (also called "dealers") use algorithms to quote continuously. There is no single designated market maker — many firms compete to provide the best quotes. The electronic model has become dominant, accounting for over 90% of US equity trading volume. Electronic market makers can update quotes in microseconds, reacting to market conditions faster than any human.
FAQs
Do market makers make a guaranteed profit?
No. Market makers take risk and can lose money. They profit on average from the spread but can suffer large losses during volatile periods when prices move against their inventory positions. In 2021, several market-making firms lost money during the GameStop short squeeze when they were forced to buy shares at rapidly rising prices while simultaneously facing margin calls. The largest market makers (Citadel, Virtu) are extremely profitable across many years, but individual trading days can produce significant losses.
How do market makers interact with retail orders?
Most retail orders are not sent to public exchanges. Instead, brokers route retail orders to market makers through a system called "internalization." The market maker pays the broker for the order flow and executes the trade from its own inventory. The market maker typically offers retail investors price improvement — a fraction of a cent better than the best available quote on public exchanges. This system, while controversial, results in retail investors receiving better prices on average than institutional investors. The SEC found that retail market orders execute at prices significantly better than the best bid or offer in 90%+ of cases.
What happens if a market maker fails?
A market maker failure can temporarily disrupt trading. If a market maker stops quoting, spreads widen and liquidity decreases until another market maker fills the gap. The most significant market maker failure was Knight Capital in 2012, which lost $460 million in 45 minutes due to a software glitch that flooded the market with erroneous orders. Knight was acquired by Getco (now Citadel Securities). The system survived because other market makers stepped in. Regulatory safeguards (risk limits, capital requirements, circuit breakers) minimize the systemic risk of a market maker failure.