Broker and Dealer: Two Functions in One Firm
Most securities firms perform both functions, but the two are economically distinct.
| Role | What They Do | Who They Serve | How They Profit |
|---|---|---|---|
| Broker | Executes trades on behalf of clients | You (the customer) | Commissions, payment for order flow |
| Dealer | Trades for their own account (proprietary trading) | Themselves | Spread between the bid and the ask |
When you submit an order, the firm may act as a broker (routing it to an exchange where it matches with another participant’s order) or as a dealer (filling it from its own inventory). The capacity in which the firm acted must be disclosed on the trade confirmation. Same firm, two hats, and the hat in use on any given trade is a fact you can verify after the fact.
How Broker-Dealers Make Money
Zero-commission trading raised an obvious question for anyone paying attention: where does the revenue actually come from? The answer is several places at once.
Payment for Order Flow (PFOF)
This is the most discussed revenue line. When you submit a market order, your broker can route it to a wholesale market maker — firms such as Citadel Securities or Virtu Financial — instead of sending it directly to an exchange. The market maker pays the broker a small fee, typically $0.001 to $0.004 per share, for the right to fill that order. The market maker then makes its own profit by filling the order at a price marginally better than the prevailing exchange quote and capturing the residual spread.
Whether PFOF is good or bad for the customer depends on framing. Defenders point to documented price improvement: the fill is often a fraction of a cent better than the best displayed exchange quote. Critics argue the conflict of interest is real and that the price improvement is smaller than what direct exchange routing would deliver, especially on size. For a small retail order, the difference is measured in pennies. For active traders moving meaningful volume, a direct-access broker that routes to exchanges is often a better fit. (In Europe the equivalent landscape is different — Trading 212, DeGiro, and IBKR operate under MiFID II rather than FINRA, and PFOF is being phased out in the EU on retail orders.)
Interest on Cash Balances
Uninvested cash sitting in a brokerage account earns interest, but the broker keeps most of the spread. If the federal funds rate is 5%, the broker may pay the customer 0.5% on idle cash and pocket the remaining 4.5%. Across billions of dollars in customer balances, this is a major revenue line and one of the reasons low-commission brokers can survive.
Margin Interest
When a customer borrows against their portfolio through a margin account, the broker charges interest, generally in the 6–12% annual range depending on the borrowed amount and the broker. This is direct lending revenue.
Securities Lending
Shares held in a customer account can be lent out to short sellers for a fee. By default, the broker keeps that fee. Some firms offer fully-paid securities lending programmes that share a portion of the proceeds with the customer who opted in, but this is not the standard arrangement.
Other Revenue
Premium data and research tiers, foreign exchange markups on cross-currency trades, account-level fees (inactivity, transfer-out, wire), and per-contract options fees ($0.50 to $0.65 at most retail brokers). Individually small, collectively material.
Choosing a Broker-Dealer
The right firm depends on the kind of trading you actually do, not the kind you imagine you might do.
| Trader Type | What to Optimise For | Examples |
|---|---|---|
| Long-term investor | Low fees, broad fund selection, retirement accounts, auto-investing | Fidelity, Vanguard, Schwab |
| Swing trader | Solid charting, stock screeners, workable margin rates, mobile app | Schwab/TD Ameritrade, E*Trade |
| Day trader | Direct-access routing, Level 2 data, hot keys, low margin rates | Interactive Brokers, Lightspeed |
| Scalper | Fastest execution, lowest per-share commissions, direct exchange routing | Interactive Brokers, Lightspeed, Cobra |
| Options trader | Low per-contract fees, options analytics, multi-leg order support | Tastytrade, Interactive Brokers |
A long-term investor who opens an account at a scalper-oriented firm pays for execution speed they will never use. A day trader at a buy-and-hold platform pays for it in slippage. Match the tool to the actual workflow.
Account Protection: SIPC and FDIC
Securities held in your account are covered by the Securities Investor Protection Corporation (SIPC):
- SIPC insures brokerage accounts up to $500,000, with a sub-limit of $250,000 for cash, against broker-dealer failure (bankruptcy or fraud at the firm level).
- SIPC does not cover market losses. A stock that drops 60% is investment risk, not broker failure, and there is no insurance for that.
- Many large brokers carry supplemental private insurance, often through Lloyd’s of London, that extends coverage well beyond SIPC limits per account.
Cash held inside a brokerage account is not FDIC-insured by default; FDIC insurance applies to bank deposits, not to broker custody. Some firms operate sweep programmes that automatically move uninvested cash into FDIC-insured partner banks, layering FDIC protection on top of SIPC. The mechanics of any specific sweep programme are worth reading once before relying on the headline number.
FINRA: The Regulator
FINRA is the self-regulatory organisation that oversees broker-dealers in the United States. Its main functions:
- Licensing of registered representatives (the Series 7 exam is the standard qualification to sell securities to the public).
- Routine examination of broker-dealer firms.
- Investigation of customer complaints.
- Enforcement of securities rules, including fines and bars from the industry.
Any broker’s disciplinary record can be checked free on FINRA’s BrokerCheck site (brokercheck.finra.org). Before funding an account, confirm the firm is FINRA-registered and read whatever regulatory actions show up. A clean record is not a guarantee of anything, but a long list of disclosures is information.
Your Rights as a Customer
- Best execution. The broker has a legal obligation to seek the best reasonably available price when executing an order. “Best” here is a regulatory standard of reasonable effort, not a guarantee of the absolute optimal fill on every trade.
- Trade confirmations. A written confirmation must be issued for every executed trade, showing price, quantity, any commission, and the capacity (broker or dealer) in which the firm acted.
- Account statements. Monthly or quarterly statements listing all positions, transactions, and the current account value.
- Arbitration. Most brokerage agreements require disputes to be resolved through FINRA arbitration rather than civil court. Arbitration is generally faster and cheaper than litigation, but it also limits the legal options that would otherwise be available.
The broker-dealer is the operational layer between the investor and the market. The trade execution, the custody of the shares, the cash sweep, the margin loan, the tax document at year-end — all of it runs through this entity. Picking the right one is less about the headline commission and more about how the firm earns its living and how its incentives line up with yours.
See also: How to Open a Brokerage Account · Order Types · What Is Margin Trading? · Short Selling Explained · Options
