Broker vs. Dealer Capacity
Overview
If you’ve ever purchased stock (or any security), you likely used the services of a broker-dealer. These firms act as intermediaries between the investing public and the financial institutions that complete trade requests (for example, market makers and clearing houses).
In 2020, these were the largest broker-dealers as measured by assets under management:
| Largest broker-dealers by AUM (2020) |
|---|
| Fidelity Investments |
| Charles Schwab |
| Wells Fargo Advisors |
| TD Ameritrade |
| Edward Jones |
You’ve probably heard of at least a few of these companies, and you might even have an account with one. Broker-dealers make it easy for investors to buy and sell many types of securities.
The name broker-dealer comes from the two different roles the firm can play when it helps a customer trade.
Definitions
🔑 Broker-dealer — legal definition in the Uniform Securities Act (USA), word-for-word:
Any person engaged in the business of effecting transactions in securities for the account of others or for his own account
| Term | Definition | Example |
|---|---|---|
| Broker-dealer | “Any person engaged in the business of effecting transactions in securities for the account of others or for his own account” | Fidelity Investments, Charles Schwab, Wells Fargo Advisors, TD Ameritrade, Edward Jones |
| Broker (agency) capacity | “A broker, or agency transaction occurs when a professional connects a buyer and seller, typically in return for a commission.” — trading “for the account of others” | A broker-dealer connects its customer with another party to buy or sell a security and earns a commission (analogy: a real estate agent earning commission on a closed home sale) |
| Dealer (principal) capacity | “A dealer, or principal transaction, occurs when a professional trades directly with a customer using the firm’s own inventory.” — trading “for his own account” | The firm buys securities from customers into inventory at a marked-down price, then sells to other customers at a marked-up price (analogy: a car dealership buying and reselling a used car) |
| Spread | “the difference between the purchase price and the sale price” | The dealer’s earnings on a principal trade — markdown on the buy, markup on the sell |
Even though the USA uses wording that sounds like it’s describing an individual (for example, “person” and “his”), you can treat a broker-dealer as a firm (a business). As you learned in a previous section, persons can be human beings or organizations.
The definition in plain English
- “Effecting transactions in securities” means the firm helps customers buy and sell securities.
- “For the account of others or for his own account” describes the two capacities a broker-dealer can use in a transaction: broker (agency) or dealer (principal).
Broker (agency) capacity
A broker, or agency transaction occurs when a professional connects a buyer and seller, typically in return for a commission.
This is what the broker-dealer definition means by trading “for the account of others.”
This idea isn’t unique to finance. Real estate brokers work the same way: if you hire an agent to help you buy a home, the agent finds a property and connects you with the seller. If the deal closes, the agent earns a commission.
Brokers in finance follow the same basic model. When a broker-dealer acts in a broker (agency) capacity, it connects its customer with another party to buy or sell a security, sometimes in return for a commission.
Commissions in practice
For decades, it was standard for securities brokers to earn commissions on the transactions they completed. Today, many large discount broker-dealers don’t charge for trades. This shift was driven in part by app-based platforms like Robinhood, which popularized $0 commission business models. Larger, well-established broker-dealers like E*Trade, Fidelity, and Charles Schwab cut many commissions to $0 in 2019 to compete.
Even though commissions are less common in practice, for test purposes you can still assume brokers earn commissions.
Dealer (principal) capacity
A dealer, or principal transaction, occurs when a professional trades directly with a customer using the firm’s own inventory.
This is what the broker-dealer definition means by trading “for his own account.”
This also isn’t unique to finance. Car dealerships operate this way. You might sell your used car to a dealership at a price slightly below its market value (a markdown). The dealership then sells the car to another customer at a price slightly above its market value (a markup). The dealer earns the spread, which is the difference between the purchase price and the sale price.
Dealers in finance work the same way. When a broker-dealer acts in a dealer (principal) capacity, it buys securities from customers into its inventory at a marked-down price, then sells those securities to other customers at a marked-up price, earning the spread.
⚠️ Broker vs. dealer — comparison
| Broker / agency capacity | Dealer / principal capacity | |
|---|---|---|
| Statutory phrase | “for the account of others” | “for his own account” |
| What the firm does | Connects a buyer and a seller | Trades directly with the customer using the firm’s own inventory |
| Compensation | Commission | Markups and markdowns (the spread) |
| Non-finance analogy | Real estate agent | Car dealership |
A broker-dealer can’t act as both broker and dealer in the same transaction, but it can act in either capacity depending on the trade.
- One trade might be an agency trade, where the firm connects a buyer and seller and earns a commission.
- The next trade might be a principal trade, where the firm sells securities out of inventory at a marked-up price.
The terms broker and dealer can sound contradictory, but they describe two different ways a firm can handle a trade.
Summary
The page includes a video borrowed from Achievable’s SIE program; the same concept applies to this material, and you could see the same type of question on this exam. A second video summarizes the key points from this chapter.
In summary, broker-dealers are firms that facilitate securities trades for customers. If a company helps you obtain or dispose of a security, it was most likely done through a broker-dealer. The next section discusses the people who work for broker-dealers.
Key points
Broker-dealer
- Any person engaged in the business of effecting transactions in securities for the account of others or for his own account
- Financial firm that helps investors trade securities
Broker/agency capacity
- ‘Trading for the accounts of others’
- Connecting buyers and sellers
- Earns a commission
Dealer/principal capacity
- ‘Trading for their own account’
- Buying into or selling out of inventory
- Earns markdowns and markups
Sources
Primary/official references for the material in this chapter. Every link was fetched and returned HTTP 200 on 2026-08-15.
| # | Source | Publisher |
|---|---|---|
| 1 | Exchange Act 1934 — broker, dealer, exchange definitions | Cornell LII (15 U.S.C. 78c) |
| 2 | Uniform Securities Act 1956 with NASAA updates — the tested statute | NASAA |
| 3 | Model rule — dishonest/unethical practices of BDs and agents | NASAA |
| 4 | Achievable Series 65 — chapter 4.2.4 | Achievable (course text) |