Broker-dealers make money in more ways than most customers realize. Commissions are only the visible layer; underneath sit markups on trades from the firm’s own inventory, payments from mutual funds, interest on margin loans and idle cash, securities lending income, payment for order flow from market makers, asset-based advisory fees, and a long tail of account and service charges. Understanding how broker-dealers make money matters because many of the largest revenue streams never appear on a trade confirmation — they’re built into prices, embedded in fund expense ratios, or earned on balances you didn’t know were being used.
The dual role is what creates the variety. A firm acts as a broker when it executes a trade on your behalf and as a dealer when it trades from its own inventory, and federal law requires any firm doing either for customers to register with the SEC and join a self-regulatory organization like FINRA.1Office of the Law Revision Counsel. 15 USC 78o – Registration and Regulation of Brokers and Dealers Each role gets paid differently.
Commissions and Transaction Fees
The simplest revenue source is still the per-trade commission. Full-service firms that provide research and personalized advice charge for each trade; Fidelity, for example, lists $32.95 for representative-assisted stock trades.2Fidelity. Fidelity Brokerage Commission and Fee Schedule Discount and online brokers have mostly eliminated commissions on domestic stocks and ETFs, which is why so many investors assume trading is free. It isn’t. The cost has moved to the revenue streams described below.
Commissions remain standard for more complex products. Options trades typically carry a per-contract fee of around $0.65.2Fidelity. Fidelity Brokerage Commission and Fee Schedule Secondary-market bond trades usually involve a per-bond charge with a minimum per trade. These fees compensate the firm for the specialized execution work those products require.
Markups and Markdowns on Principal Trades
When the firm sells you a security out of its own inventory instead of finding another seller in the market, it adds a markup: the gap between what the security costs in the wholesale market and the price you pay. When you sell, the firm buys from you at a markdown below the current market price. That spread is how the firm gets paid for carrying inventory and providing immediate liquidity.
You’ll see this most with municipal bonds, corporate bonds, and over-the-counter stocks. Those products trade less often than exchange-listed shares, their quoted prices are less transparent, and the spreads are wider. FINRA Rule 2121 requires markups and markdowns to be fair in light of current market conditions, the cost of executing the trade, and the nature of the firm’s business.3FINRA. FINRA Rule 2121 – Fair Prices and Commissions “Fair” leaves room for judgment, though, and a retail investor buying a thinly traded bond rarely knows what the firm paid for it an hour earlier.
Payment for Order Flow
Payment for order flow is what replaced commissions for most retail stock trading, and it’s the most debated piece of broker-dealer compensation. When you place a stock order through a zero-commission broker, the firm routes the order to a market maker that pays the broker a small fraction of a cent per share to fill it. Retail orders are desirable because individual investors trade in smaller, more predictable sizes than institutional traders.
Your visible cost stays at zero. The open question is whether the market maker is giving you a slightly worse execution price than you’d get on an exchange. SEC Rule 606 addresses the transparency side by requiring broker-dealers to publish quarterly reports showing where they route orders, what compensation they receive from each venue, and the terms of any profit-sharing or volume-based arrangements. Those reports must stay on a publicly accessible website for three years.4U.S. Securities and Exchange Commission. Responses to Frequently Asked Questions Concerning Rule 606 of Regulation NMS
SEC Rule 605 complements this by requiring market centers to publish monthly execution-quality statistics, including the share of orders that received price improvement and the average amount of that improvement.5eCFR. 17 CFR 242.605 – Disclosure of Order Execution Information Comparing your broker’s Rule 606 disclosures against the Rule 605 data from its execution venues is how you’d actually evaluate whether the arrangement is costing you money. Few retail investors do.
Interest on Margin Loans and Uninvested Cash
Interest income is the steadiest and often the largest line for a broker-dealer. It comes from two places.
Margin Lending
When you borrow against your portfolio to buy more securities, the firm is extending a margin loan. Federal Reserve Regulation T sets the initial margin requirement at 50%, so you must put up at least half the purchase price in cash or eligible securities before the firm lends the rest.6Federal Reserve Board. Background and Summary of Regulation T The rate charged on that loan is typically several percentage points above the federal funds rate, and the spread between what the firm pays to fund the loan and what it charges you is profit. These loans have no fixed repayment schedule, so interest keeps accruing for as long as you hold the leveraged position.
Uninvested Cash
The other side is the cash sitting in customer accounts between investments. When you sell a stock and leave the proceeds in your brokerage account, or when a dividend lands before you reinvest it, the firm sweeps that money into short-term instruments like Treasury bills or money market funds. The firm earns the prevailing short-term rate and pays you a lower rate, or sometimes nothing. The gap is called net interest margin. Any single balance is small; aggregated across millions of accounts, these balances represent billions in investable capital. When short-term rates are high, cash sweep revenue can become a firm’s single largest income line.
Securities Lending
If you hold stocks in a margin account, your broker-dealer can lend those shares to other market participants, typically short sellers who need to borrow shares before selling them. The borrower pays interest on the loan, and the firm keeps a portion of that income. For shares in high demand, lending fees can be substantial.
SEC Rule 15c3-3 governs how this works. The borrower must post collateral equal to or exceeding the value of the borrowed securities, and the agreement must spell out the compensation terms and the parties’ rights in writing.7eCFR. 17 CFR 240.15c3-3 – Customer Protection – Reserves and Custody of Securities For shares in a margin account, you generally agreed in the margin paperwork that the firm can lend them without asking each time.
Some firms also run fully paid lending programs that lend securities from your cash account in exchange for splitting the interest income with you. These require a separate written agreement and the firm must fully collateralize the loan.8U.S. Securities and Exchange Commission. Staff Statement on Fully Paid Lending A roughly 50/50 split is typical. Whether the income is worth having your shares out on loan depends on what you own; fees on widely held blue chips are negligible, while fees on volatile or hard-to-borrow names can be meaningful.
Mutual Fund Distribution and 12b-1 Fees
When a broker sells you mutual fund shares, the fund itself often pays the firm, both for distribution and for ongoing account servicing. Those payments come straight out of the fund’s assets, so you never see them on a confirmation. The asset-based distribution fee, commonly called a 12b-1 fee, is capped at 0.75% of the fund’s average annual net assets. On top of that, funds may pay the broker a service fee of up to 0.25% annually for maintaining shareholder accounts.9FINRA.org. FINRA Rule 2341 – Investment Company Securities Combined, that’s up to 1% of your invested balance flowing from the fund to the broker each year, buried in the expense ratio.
This arrangement gives brokers an incentive to recommend funds with higher 12b-1 charges over cheaper alternatives, which matters when no-load index funds with minimal expense ratios are widely available. FINRA caps total sales charges — including front-end loads, deferred loads, and asset-based fees — at 6.25% of total new gross sales for funds that pay service fees, which limits how much a firm can extract across the life of your investment.9FINRA.org. FINRA Rule 2341 – Investment Company Securities
Wrap Fee Advisory Programs
Many broker-dealers have moved toward an asset-based model, charging a single annual fee of roughly 1% to 3% of assets under management that bundles trading, advice, and administration into one number. These wrap programs have become a dominant line at firms serving wealthier clients because the fee grows with the account value, no new trades required.
Firms that sponsor wrap programs must register as investment advisers and deliver a wrap fee brochure (Form ADV Part 2A, Appendix 1) to clients before or when the advisory relationship begins.10eCFR. 17 CFR 275.204-3 – Delivery of Brochures and Brochure Supplements That brochure spells out exactly what’s included and what sits outside the fee. The appeal is cost predictability. The risk is paying 1% to 2% a year on a portfolio that barely trades, which can cost more than occasional commissions would have.
Underwriting and Investment Banking
The institutional side of the business generates income most retail customers never see. When a company goes public, the broker-dealer acting as underwriter buys the shares from the issuer at a discount and resells them to the public at the offering price. That “gross spread” typically runs 4% to 7% of total IPO proceeds for mid-sized offerings and drops below that on billion-dollar deals where competition among underwriters pushes the fee down. The same structure applies to debt offerings for corporations and municipalities.
Underwriting carries real risk. The firm commits to buying the entire issuance from the company, and if demand falls short, the firm is left holding unsold securities at a loss. Large offerings are usually shared among a syndicate that splits both the fees and the risk.
Advisory fees from mergers and acquisitions round out the investment banking line. Firms charge success fees, usually a percentage of the deal’s total value, for advising on acquisitions, divestitures, and restructurings. Those engagements can run months and the fees compensate for both the expertise and the senior-banker time tied up in a single transaction.
Account and Regulatory Fees
A long tail of smaller charges rounds out the firm’s revenue. Some are regulatory pass-throughs; others are set by the firm.
Regulatory Pass-Through Fees
Two show up on nearly every sell transaction. The SEC Section 31 fee funds the SEC’s operations and is set at $20.60 per million dollars of covered sales, effective April 4, 2026, which works out to about two cents on a $10,000 stock sale.11U.S. Securities and Exchange Commission. Section 31 Transaction Fee Rate Advisory for Fiscal Year 2026 The FINRA Trading Activity Fee is $0.000195 per share for equities, capped at $9.79 per trade, and $0.00329 per options contract.12FINRA.org. FINRA Fee Adjustment Schedule Tiny on any single trade, these fund the regulatory infrastructure in aggregate.
Account and Service Fees
Firms also set their own account-level charges. Common ones include:
- Account maintenance fees, often $25 to $100 a year on specialized or low-balance accounts like IRAs.
- Wire transfer fees, typically $20 to $35 per outbound domestic transfer.
- Account transfer fees, charged when you move your account to another firm through the automated transfer system (ACATS). The underlying clearinghouse cost is roughly $0.50, but firms routinely charge $50 to $150.
- Paper statement fees, small charges meant to push customers toward electronic delivery.
- Reorganization fees, charged for processing mergers, tender offers, and spinoffs that require manual account updates.
None of these alone amounts to much, but they add up and hit smaller accounts hardest as a percentage of assets. Reading the fee schedule before opening an account is the only way to avoid being surprised later.
How to See What You’re Actually Paying
Federal rules require broker-dealers to tell you how they get paid, but you have to know where to look. Every broker-dealer serving retail investors must prepare and deliver a relationship summary called Form CRS, which discloses the firm’s services, fees, conflicts of interest, and disciplinary history in a standardized format. The firm must provide it before making any recommendation, opening an account, or placing an order for you — whichever comes first — and must post it prominently on its website.13eCFR. 17 CFR 240.17a-14 – Form CRS
The SEC’s Regulation Best Interest goes further than disclosure. It requires broker-dealers to act in your best interest when recommending securities, strategies, or account types, replacing the older “suitability” standard that only required a recommendation to be generally appropriate.14FINRA.org. SEC Regulation Best Interest The best-interest standard requires firms to address conflicts of interest like 12b-1 fees and payment for order flow, not just mention them. If a firm recommends a higher-cost product when a cheaper equivalent exists, Reg BI gives you a basis to challenge that recommendation.
Reading your firm’s Form CRS, its mutual fund prospectuses for 12b-1 fee levels, its Rule 606 order-routing report, and its published fee schedule covers most of what’s being charged against you, visibly and invisibly. The revenue streams are legal and disclosed. Whether they’re worth what you’re paying is a question only the disclosures can answer.