Module I·Article II·~4 min read
Trading Venues: Exchanges and Alternative Trading Systems
Structure of Financial Markets and Infrastructure
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Exchanges and Alternative Trading Venues
Trading venues play a key role in the functioning of financial markets, providing the infrastructure for buyers and sellers to meet, for price formation, and for the execution of transactions. The evolution of technology has led to the emergence of various types of trading venues with different characteristics.
Traditional Exchanges
Stock exchanges historically emerged as physical venues where brokers met to trade securities. The New York Stock Exchange (NYSE), founded in 1792, for a long time remained a symbol of the trading floor, with shouting brokers and manual matching of orders. Modern exchanges have transformed into high-tech electronic platforms. Even NYSE, while maintaining a traditional trading floor, conducts the overwhelming majority of operations electronically. Exchanges perform several key functions: they provide a price formation mechanism through order matching, establish rules for trading and listing, supervise participants, and provide market data.
Trading Models on Exchanges
Order-driven market — a model in which prices are formed based on the interaction of buy and sell orders in the order book. Examples are most modern electronic exchanges: NASDAQ, LSE, Moscow Exchange.
Quote-driven market — a model in which market makers continuously post two-sided bid and ask quotes at which they are ready to trade. A classic example was the NASDAQ system before the transition to a hybrid model.
Hybrid models combine elements of both approaches: the electronic order book is supplemented by obligations of market makers to provide liquidity. NYSE uses designated market makers (DMM), who are required to maintain fair and orderly markets for the stocks assigned to them.
Alternative Trading Systems (ATS)
Alternative Trading Systems (ATS) are electronic trading platforms that do not have exchange status but perform the function of matching orders. In the US, ATS are regulated by the SEC under Regulation ATS. In Europe, similar structures are called Multilateral Trading Facilities (MTF). ATS emerged in response to the needs of institutional investors for more efficient execution of large orders with less market impact. Many ATS specialize in specific types of clients or execution strategies.
Dark Pools
Dark pools are a type of ATS that do not display quotes publicly before a trade is executed. The name comes from the opacity of the order book (“dark” liquidity as opposed to “lit” liquidity of public exchanges). The main advantage of dark pools is the ability to execute large orders without disclosing trading intentions. When an institutional investor plans to buy a significant block of shares, placing an order on a public exchange can lead to adverse price movement—traders will see the large order and start buying ahead of it. In a dark pool, orders are matched anonymously, often at the midpoint between bid and ask (midpoint matching). This allows large investors to save on the spread and minimize market impact.
Critics of dark pools point to risks to fair price formation—a significant volume of trading occurs outside public markets, potentially reducing the quality of price signals. Regulators in the US and Europe have intensified oversight of dark pools, requiring greater transparency and limiting the trading volume in non-public systems.
Electronic Communication Networks (ECN)
ECN are electronic systems that automatically match buy and sell orders. Unlike traditional exchanges, ECN were originally created as fully electronic platforms without a physical trading floor. ECNs typically offer a transparent order book, low commissions, and high execution speed. Many ECNs are integrated with major exchanges or have been acquired by them—for example, Archipelago was acquired by NYSE, and Instinet is owned by NASDAQ.
Systematic Internalisers
Systematic Internalisers (SI) are investment firms that regularly execute client orders against their own positions outside regulated markets. The concept was introduced by the European MiFID directive. SIs effectively act as a counterparty in the transaction, offering clients execution at prices comparable to or better than those on public venues. This allows major banks and brokers to internalize client flow, but creates potential conflicts of interest.
Competition Between Venues
Fragmentation of trading across multiple venues creates both advantages (competition reduces costs) and challenges (complexity of finding the best price, technological costs of connectivity). Smart Order Routing (SOR) is a technology that allows orders to be automatically directed to the venue with the best execution conditions. SOR algorithms analyze liquidity, spreads, and commissions on many venues in real time.
Regulatory best execution requirements obligate brokers to provide the best execution of client orders, taking into account price, speed, likelihood of execution, and overall costs. This stimulates the use of liquidity aggregation and smart routing technologies.
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