Trading Technology
How Market Makers Provide Liquidity
When you hit 'buy,' someone is instantly on the other side. Who, why, and how they make money doing it.
Click buy on any liquid stock and it fills in milliseconds — even though no other retail human happened to be selling at that instant. A market maker was. Understanding them explains a huge amount about how modern markets actually work.
The spread is the business
A market maker continuously quotes two prices: a bid (what they'll pay) and an ask (what they'll sell for). The gap is the spread.
How it works
- YOU SUBMIT ORDER
- MARKET MAKER QUOTES BID/ASK
- YOU FILL AT THE ASK
- MM HEDGES INVENTORY
- MM EARNS THE SPREAD
They aren't betting on direction. They're getting paid to be there — to absorb your order now and manage the inventory risk after.
Why fills feel free
Payment for order flow
Your 'free' brokerage often routes your order to a market maker who pays for it. You get a fast fill; the market maker gets predictable retail flow it can profit from. That's the trade.
Inventory risk is the real game
The danger isn't a single trade — it's holding a position when the market moves against you before you can hedge. Everything a market maker does is about managing that inventory in real time.
Key takeaway
Market makers earn the spread for providing immediacy and absorbing inventory risk — not by predicting direction. Liquidity is a service, and someone is always being paid to supply it.