What Is a Broker? Definition, Types, How They Make Money

You’ve probably used a broker without thinking about it — whether buying a house, trading a stock, or getting car insurance. These intermediaries sit between buyers and sellers, making transactions happen for a fee. This guide breaks down what a broker does across industries, how they earn their cut, and the trade-offs you should know before hiring one.

Broker commission range: 1-3% of transaction value ·
Fractional shares at top brokerages: Available since 2019 ·
U.S. broker-dealers registered with SEC: Over 3,400 ·
Average annual salary of a stockbroker (U.S.): $72,000 – $150,000

Here’s a quick reference on broker fundamentals.

What exactly does a broker do?

A broker is a person or firm that arranges transactions between a buyer and a seller, taking a commission when the deal goes through. The role is fundamentally that of a neutral intermediary — the broker doesn’t own the assets being traded, they simply connect the two sides.

Explain the role of intermediary

• Matches buyers and sellers in markets like stocks, real estate, insurance, and shipping (Wikipedia (encyclopedia))
• Provides liquidity by helping participants find counterparties quickly (Remitly (international finance guide))
• Handles research, negotiation, and paperwork for clients (Remitly)

List key functions of a broker

• Order execution – buying/selling securities on an exchange
• Market advice – recommending investments (only full-service brokers)
• Regulatory compliance – ensuring all trades meet legal requirements (SmartAsset)
• Administration – managing paperwork, clearing, and settlement

The pattern: each function adds a layer of service that justifies the fee.

How do brokers make money?

Brokerage compensation models vary by industry and service level. Understanding how your broker gets paid helps you spot potential conflicts of interest.

Commission models

• Per-trade commission: A fixed fee for each buy or sell order (e.g., $4.95 per trade at many discount brokers) (Forage (career education platform))
• Percentage of transaction: Common in real estate (typically 5-6% of sale price) and insurance (commissions embedded in premiums) (Insureon (small business insurance resource))

Fee structures

• Flat annual or monthly fee: Some brokers charge a subscription for unlimited trades (e.g., Interactive Brokers’ tiered plans)
• Asset-based fee: A percentage of assets under management (AUM), typical for full-service financial advisors

Markup and spreads

• Forex brokers often profit from the bid-ask spread rather than a visible commission (Remitly)
• Insurance brokers earn commissions from insurers as a percentage of premiums — a model that can incentivize pushing pricier policies

The implication: your broker’s compensation model directly shapes their recommendations—always ask how they get paid before signing up.

Why would someone use a broker?

Despite the fees, brokers remain essential for many investors and consumers. The reasons boil down to three core benefits: access, expertise, and time.

Access to markets

• Retail investors cannot directly trade on major exchanges (NYSE, NASDAQ) without a broker (Forage)
• Insurance buyers need a broker to compare policies across multiple carriers (Insureon)
• Real estate listings are often shared only through broker networks (MLS)

Expert advice

• Full-service brokers provide research reports, portfolio analysis, and tax strategies (Forage)
• Insurance brokers advise on coverage gaps and hidden exclusions (Goodwin University (insurance education resource))
• Real estate brokers guide pricing, negotiation, and legal contingencies

Time savings

• Brokers handle the legwork of searching for counterparties, collecting paperwork, and managing compliance
• Shipping brokers arrange cargo transport across international routes, sparing companies from dealing with individual carriers

The implication: for most people, the cost of a broker is offset by the value of expert execution and market access — but only if you pick the right type.

Who are the big 4 brokers?

The brokerage industry is concentrated among a handful of giants. In stock trading, the Big 4 dominate retail assets. In insurance, a different Big 5 rules commercial lines.

Largest stock brokerage firms

• Fidelity Investments – largest by assets under administration, offering commission-free trades and fractional shares
• Charles Schwab – merged with TD Ameritrade in 2020, now serving over 30 million brokerage accounts
• Vanguard – known for low-cost index funds and ETFs; also offers brokerage services
• E*TRADE – a pioneer in online trading, now owned by Morgan Stanley

These four collectively hold the majority of retail brokerage assets in the U.S. SmartAsset (personal finance authority) notes that market share shifts monthly as brokerage mergers and promotions change customer preferences.

Big 5 in insurance brokerage

• Marsh & McLennan
• Aon
• Willis Towers Watson (WTW)
• Arthur J. Gallagher
• Brown & Brown

These firms dominate commercial insurance brokerage, advising large corporations on risk management and employee benefits.

The pattern: the largest firms win on scale and resources; smaller brokers win on specialization and attention—choose accordingly.

What are the risks of using a broker?

Using a broker isn’t risk-free. Conflicts of interest, hidden fees, and operational failures can cost you money or opportunity.

Conflict of interest

• Brokers earning per-trade commissions may recommend unnecessary trades (AgentSync (insurance compliance platform))
• Insurance brokers who receive higher commissions from certain carriers may push those policies even if they aren’t the best fit
• Real estate brokers incentivized by percentage of sale price may push for a quick sale rather than a higher price

Hidden fees

• Account maintenance fees, inactivity fees, and transfer-out fees can erode small accounts
• Forex brokers may hide costs in wide spreads (Remitly)
• Insurance brokers sometimes add administrative fees to policies

Platform outages and slippage

• Retail broker platforms have experienced outages during high volatility (e.g., GameStop surge in 2021)
• Order execution can slip on fast-moving markets, costing more than expected

The catch: the upsides depend entirely on picking the right broker type for your needs—a mismatch can turn benefits into costs.

Quotes from trusted sources

“A broker is a person or entity that arranges transactions between a buyer and a seller, typically for a commission.”

– Wikipedia (encyclopedia)

“A broker is a financial intermediary who connects investors with capital markets.”

– ESADE University (business school) (as cited in broker explanations)

“Retail intermediaries (brokers) advise consumers on financial products.”

– Central Bank of Ireland (regulatory authority)

For investors tracking the broader market, see our analysis of S&P 500 Today. If you deal with currency exchange, our guide A Como Esta El Dolar – Current Argentina Exchange Rates provides context on forex broker dynamics.

For mortgage brokers, platforms like the Westpac Broker Hub provide essential tools for managing loan applications and client communications.

Frequently asked questions