Broker
The firm that routes your orders to the market and holds your account.
Also called: brokerage · trading platform
Written by Javier Sánchez Ros
In plain language
A broker sits between you and the exchange. They accept your orders, route them for execution, hold your cash and positions, and apply margin rules to your account.
Brokers differ in ways that directly change your results: commission structure, spread markup, execution quality, available order types, margin rates, and what happens to your position when you breach a margin requirement.
Every broker also imposes its own risk controls. Understanding when they will liquidate your position for you is part of understanding your own risk.
Worked through
What a "zero commission" account still charges
- Commission
- $0
- Spread
- on every round trip
- Overnight financing
- daily on leverage
- Currency conversion
- on non-base trades
Zero commission is accurate and it is one line of four. The spread is a cost whether or not anyone calls it one; financing accrues nightly on anything leveraged; and buying a foreign-listed instrument converts currency twice, at a rate the broker sets. None of these appear as a fee on the statement.
Then there are the rules that matter more than the costs. At what equity level does the broker issue a margin call, and does it call first or liquidate immediately? Which positions does it choose to close? Is your cash segregated from the firm’s own money, and what protection scheme covers the account if the firm fails?
These are answered in the account documentation and almost nobody reads them until the answer is being applied to their account in real time. They are the terms under which your trade can be ended without your consent, which makes them part of your risk model rather than paperwork.
A broker is not a neutral pipe to the market. It is a counterparty with its own rules, its own costs and its own solvency, and all three sit underneath every position you hold there.
Why it matters
Your broker defines the real cost of every trade and the exact rules under which your position can be closed without your consent.
Common mistakes
- Comparing brokers on headline commission while ignoring spreads and financing costs.
- Not knowing the margin call and forced-liquidation policy until it is triggered.
Keep exploring
These concepts are connected. Understanding one usually makes the next one easier.
The capital your broker requires you to post to open and hold a leveraged position.
A broker demand for more capital when account equity falls below the required minimum.
The gap between the bid and the ask — the built-in cost of entering a trade.
The instruction that says how long an order stays active before it expires.
A US regulatory designation for accounts making four or more day trades in five business days.