Exchanges, venues and brokers: who sits between you and the market

What you will learn

• The chain of firms between your order and the final transfer of securities: broker, venue, clearing house, central securities depository and custodian.
• The four types of EU trading venue and how order-driven and quote-driven markets differ.
• Whether your broker acts as an agent or as your counterparty, and why it matters.
• How to compare two execution routes by total cost, not by the fee alone.

Explanation

Listings and trading hours were covered in the course "Stocks" (lesson "How stock exchanges work"). Here we follow a single order.

The chain behind one order

1. Broker: a licensed investment firm or bank that accepts your order and sends it on.
2. Trading venue: the place where buyer and seller are matched.
3. Central counterparty (CCP): a clearing house that steps between buyer and seller on many exchanges, so each side faces the CCP instead of an unknown firm. Clearing means netting and guaranteeing trades until settlement.
4. Central securities depository (CSD): the institution that records who owns which securities and moves them against cash. This final exchange is called settlement.
5. Custodian: the bank holding the securities for you, often your broker's partner bank.

In the EU, share trades currently settle two business days after the trade date (T+2). The EU has decided to move to T+1 on 11 October 2027; check the current status before relying on a date.

Four types of EU venue

The EU rulebook for investment services (MiFID II, the Markets in Financial Instruments Directive) defines:

• Regulated market (RM): a classic exchange, for example Xetra or Börse Frankfurt.
• Multilateral trading facility (MTF): a system run by an investment firm or market operator that also matches many buyers and sellers under fixed rules.
• Organised trading facility (OTF): used for bonds and derivatives, not shares; the operator has some matching discretion.
• Systematic internaliser (SI): a single firm that trades against its clients' orders on its own account on a regular basis.

Trades outside all of these are called over-the-counter (OTC).

Order-driven versus quote-driven

In an order-driven market, all participants' limit orders meet in one central limit order book. Xetra works this way. In a quote-driven market, one market maker or specialist continuously quotes a bid (buy) and an ask (sell) price, and you trade against those quotes. Several German venues used by low-cost brokers work mainly this way (see lesson 3).

Agent or counterparty?

As an agent, a broker sends your order to a venue where another participant takes the other side. As a principal, a firm is itself your counterparty and trades from its own account. A CFD (contract for difference) provider is always your counterparty, because a CFD is a private contract with that firm. CFDs are leveraged and can lose money quickly. A principal earns from the spread, so its prices and your interests are not automatically aligned. Many neo-brokers also route nearly all orders to one partner venue; whether the broker receives payments for this is covered in lesson 7.

Worked example

Hypothetical example: you want to buy a share whose fair middle price (mid) is €50.00. Two routes are available:

The half-spread (mid to the price you pay) is a real cost, even though no invoice shows it.

Order of 40 shares:

• Route A: 40 × €0.02 = €0.80 spread + €6.40 fees = €7.20
• Route B: 40 × €0.05 = €2.00 spread + €1.00 fee = €3.00

Order of 400 shares:

• Route A: 400 × €0.02 = €8.00 + €6.40 = €14.40
• Route B: 400 × €0.05 = €20.00 + €1.00 = €21.00

Break-even size: route B saves €6.40 − €1.00 = €5.40 in fees but costs €0.05 − €0.02 = €0.03 more per share. €5.40 ÷ €0.03 = 180 shares. Below 180 shares route B is cheaper; above it, route A is cheaper.

Assumptions: quotes stay unchanged and the whole order fills at the best price. Excluded: taxes and price movement during execution.

Common mistake

Practice activity

1. Who is your counterparty when (a) you buy shares in the Xetra order book through a CCP, (b) you buy a CFD on the same share, (c) you trade against a market maker's quote on a quote-driven venue?
2. Hypothetical: route A has a half-spread of €0.01 and fees of €8.00; route B has a half-spread of €0.04 and a fee of €1.00. Find the break-even size and the total cost of each route for 300 shares.

Key takeaways

• An order passes through a broker, a venue and, for exchange trades, a clearing house and a depository before you own the securities.
• EU venues are regulated markets, MTFs, OTFs and systematic internalisers; trades outside them are OTC.
• Know whether a firm is your agent or your counterparty; with CFDs it is always the counterparty.
• Total cost = half-spread × shares + all fees; the cheapest route depends on order size.

Next step

In the next lesson you will open the order book itself and measure bids, asks, depth and the spread.