Module III·Article I·~4 min read
Broker vs Dealer: Agency and Principal Transactions
Brokers, Dealers, and Market Makers
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Differences Between Broker and Dealer Models Understanding the differences between a broker and a dealer is fundamental for navigating the financial industry. These two roles imply different obligations, risks, and sources of income, although in practice many firms combine both functions.
Broker: Agency Model
A broker acts as an agent of the client, executing transactions on the client’s behalf and at their expense. The broker does not become the owner of the traded assets—they merely transmit the client’s order to the market and ensure its execution.
Legal status: In an agency transaction, the broker represents the interests of the client. This creates fiduciary duties—the broker must act in the best interests of the client. The best execution obligation requires seeking the best possible execution conditions.
Sources of broker’s income:
- commission—a fixed fee or percentage of the transaction volume;
- markup/markdown—the difference between the execution price and the price presented to the client (must be disclosed);
- trading and research access fees;
- interest on client cash balances.
Broker risks:
- operational risk (execution errors),
- legal/compliance risk (breach of obligations towards the client),
- credit risk (client insolvency in unsettled trades).
The broker does not bear market risk—profits and losses from price changes belong to the client.
Dealer: Principal Model
A dealer trades on their own account, becoming the owner of the assets. In a principal transaction, the dealer is the client’s counterparty, not their representative. The dealer purchases the asset for their own ownership and sells from their inventory.
Legal status: In a principal transaction, the dealer acts on their own behalf. Fiduciary obligations are weaker, but regulation still requires fair dealing and disclosure.
Sources of dealer’s income:
- bid-ask spread—the difference between the buying and selling price;
- trading profits—profits from directional positions;
- inventory appreciation—increase in the value of holdings.
The dealer earns by providing liquidity to the market.
Dealer risks:
- market risk—changes in the value of inventory;
- inventory risk—accumulation of unwanted positions;
- counterparty risk—client default before settlement;
- funding risk—cost of financing positions.
Broker-Dealer: Hybrid Model
Most large financial institutions operate as broker-dealers, combining both roles. This allows them to offer clients a full range of services: agency execution for standard orders, principal trades for large blocks or illiquid instruments.
Conflicts of interest: Combining roles creates potential conflicts. Acting as principal, the firm may have interests opposed to those of the client. Regulation requires disclosure of the capacity in which the firm acts, and management of conflicts.
Chinese walls (information barriers): Separation between departments with access to different information. For example, the trading desk must not receive information from investment banking about upcoming M&A deals.
Practical Differences in Execution
Agency execution: The client places an order, the broker transmits it to the exchange or another venue, and the order is executed at the market price. The broker charges commission on top of the execution price. Transparency is high—the client sees the execution price.
Principal execution: The client requests a quote, the dealer quotes bid/ask from their own position. The client decides whether to accept the quote. The price already includes the spread—additional commission may not be charged. The client receives guaranteed execution, but may not know the “fair” price.
Riskless principal: A hybrid format where the dealer executes the client’s order on the market, simultaneously recording a mirror transaction with the client. Technically this is a principal trade, but without market risk for the dealer. Used for transparency and compliance reasons.
Regulatory Requirements
Registration: Broker-dealers must be registered with the SEC (USA), FCA (UK), and relevant regulators in other jurisdictions. Registration implies capital requirements, compliance obligations, and reporting.
Capital requirements: Dealers must maintain minimum capital to cover risks. The net capital rule in the USA (Rule 15c3-1) sets requirements based on business type and positions.
Customer protection: Rule 15c3-3 in the USA requires segregation of client assets from proprietary assets of the firm. This protects clients in the event of broker-dealer bankruptcy.
Best execution: Obligation to ensure the best execution of client orders. Criteria include price, speed, and likelihood of execution. Broker-dealers must regularly review execution quality and venue selection.
Evolution of the Business Model
Electronification: Automation of trading and connectivity with multiple venues has changed the role of brokers. Algorithms execute most orders, reducing the significance of human traders.
Unbundling: Historically, research and execution were bundled in one commission. Regulation (MiFID II in Europe) requires separation—clients must explicitly pay for research. This changed the economics of sell-side research.
Principal vs agency shift: Regulation (Volcker Rule) has limited proprietary trading by banks. Many dealer desks have reoriented toward client-driven flow, acting more as agents or riskless principals.
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