1. Financial Markets#

Financial markets address a perennial challenge faced by societies: the efficient allocation of savings toward productive uses. Individuals and institutions with excess funds aim to achieve the highest returns (investment) while maintaining maximum liquidity. Consequently, they often prefer to lend money on a short-term basis. Conversely, those requiring capital—whether to launch new ventures, expand existing businesses, acquire assets such as homes through mortgages, or finance social programs—seek to secure funds at minimal cost and for extended periods. Without a mechanism to reconcile these opposing objectives, surplus funds may remain idle, hindering their potential to contribute to economic productivity.

Modern capitalist societies solve this problem in two ways, which form the backbone of the financial system: the banking system and financial markets.

1.1. The Banking System#

In the banking system the center is the bank, an institution or private company that offers short-term deposits with high availability to those with excess funds, and long-term loans to those who need funds. A capital cushion based on short-term loans or directly cash is maintained in order to fulfills withdrawals. Their activity is not exempt from risks:

  • liquidity risk, which can happens if the demand to withdraw deposits exceeds the capital cushion, and depositors cannot be satisfied (bank run)

  • credit risk, which happens when borrowers of funds default on their obligations and don’t give back those funds.

Banks compensate those risks by charging a spread between interest of loans and interest of deposits, on top of a margin to pay for their operations. The banking system has traditionally being the central core of the financial system in Europe.

1.2. Financial markets#

In financial markets, those who need funds issue financial instruments, legally binding contracts that articulate the terms in which those funds will be returned to the investor, as well as the compensation for the service. So far that is not that different from traditional banking loans. The key for financial instruments is the possibility of transferring the property of the contract, i.e. the right to receive back those future cash-flows and compensations. This provides a mechanism for the lender to potentially recover the funds before the contract ends, solving the problem of liquidity even if contracts are issued with long-term horizons.

Of course, for that the lender needs to find a counterpart that is willing to purchase the financial instrument, and agree to the price. Pricing financial instruments is however not a simple task, since their value depend on assumptions about the certainty of those future cash-flows (for instance, what if the borrower cannot commit in the future to pay back?). There are also considerations of opportunity costs, since the potential investor will necessarily compare the return on its investment when acquiring the financial instrument with other potential productive uses of her money. Financial markets developed precisely to solve these two problems: 1) finding counterparts, 2) setting a price.

Financial markets are the place where interested parties meet and negotiate the prices of financial instruments. In primary markets, financial instruments are issued by the borrowers and acquire initially by investors, sometimes via intermediaries like banks. In secondary markets, already issued financial instruments are negotiated between investors, with the original borrower not playing any part any more in the process. Most of trading nowadays occurs in secondary markets.

In this process, financial markets not only provide of a mechanism for investors to obtain liquidity from their investments, but also serve as a mechanism for price discovery. In the end, in financial markets (as in other markets), the price of a financial instrument is what two willing parties agree to transact, independently of the subjective value that each of them place on the instrument. Of course, by pulling multiple investors in the same place to negotiate, financial markets channel multiple speculative ways about the value of a financial instrument into an actual price. These prices can guide investors about future decisions.

1.3. Who Participates in Financial Markets?#

Financial markets primarily involve legal entities, although natural persons—individuals—may also participate, typically through intermediaries such as banks or brokers. The core participants issuing financial instruments are varied: corporations issue securities to fund their business activities, while governments at all levels—local, regional, national, and supranational—issue bonds to finance social programs or public investments. Additionally, banks design and issue customized products aimed at meeting the investment needs of institutional and individual investors.

On the demand side, institutional investors such as hedge funds, mutual funds, pension funds, and insurance companies play a crucial role in acquiring financial instruments. Their goal is either to generate returns for their clients or manage specific risks. Corporations also buy financial instruments, both to make their excess cash productive and to hedge against business risks. Similarly, banks acquire these instruments as part of their liquidity management strategy, to generate returns on customer deposits, and to mitigate various financial risks. Central banks are key participants as well, utilizing financial instruments to execute their monetary policies, influencing money supply and interest rates.

In terms of intermediation, banks and brokers facilitate market transactions. Banks, particularly in their role as market-makers, are key liquidity providers. They stand ready to buy or sell financial instruments, profiting from the spread—the difference between the buying and selling price—which compensates them for holding the instrument until an opposing counterparty emerges. Brokers, on the other hand, connect buyers and sellers through their networks or proprietary platforms, charging a fee for their matchmaking services without holding the financial instruments themselves.

An increasingly important role in financial markets today is played by new liquidity providers—technology-driven financial firms. Many of these firms originated from high-frequency trading and now use advanced algorithms to provide liquidity in electronic markets. This new breed of liquidity providers competes with traditional market-makers, leveraging automation and sophisticated trading strategies to ensure tighter spreads and more efficient markets.

1.4. Types of Financial Instruments and Asset Classes#

Financial instruments are the building blocks of financial markets, representing the contracts or securities through which money flows. These instruments are typically grouped into distinct asset classes based on their characteristics, the types of returns they provide, and the markets they operate within. Understanding the different types of financial instruments and asset classes is essential for comprehending how financial markets function and how participants make investment decisions.

The major asset classes include equity, fixed income, money markets, derivatives, foreign exchange (FX), commodities, and cryptocurrencies. Each asset class plays a distinct role in the financial ecosystem, catering to different investor needs, risk appetites, and financial goals.

1.4.1. Equity and Fixed Income#

The most well-known financial instruments are stocks and bonds, which form the foundation of two major asset classes: equity and fixed income.

  • Stocks represent ownership in a corporation and give investors a claim on a portion of the company’s assets and earnings. Stocks are part of the equity asset class, providing potential for capital appreciation and dividends. However, they also expose investors to market volatility and business risk, making them a relatively high-risk, high-reward investment.

  • Bonds, on the other hand, are debt securities issued by governments, corporations, or other entities to raise capital. Investors in bonds lend money to the issuer in exchange for periodic interest payments and the return of the bond’s face value at maturity. Bonds belong to the fixed income asset class, which generally offers stable and predictable returns, although they are still subject to risks such as interest rate fluctuations and credit defaults.

Both stocks and bonds are often referred to as cash instruments, meaning their value derives directly from the underlying market dynamics, without the need for an intermediary asset.

1.4.2. Money Markets#

Within the fixed income category, there is a sub-sector known as the money market, which some consider an asset class of its own due to its distinct features. Money market instruments are short-term debt securities that typically mature in less than a year, such as Treasury bills, commercial paper, and certificates of deposit. These instruments are highly liquid and relatively low-risk, making them an attractive option for institutions and governments looking to manage short-term liquidity needs, as well as for investors seeking a safe place to park cash temporarily.

1.4.3. Derivatives#

Derivatives are financial contracts whose value is derived from the performance of an underlying asset, index, or rate. They can be based on a wide range of underlying assets, including stocks, bonds, commodities, currencies, and interest rates. This is why some categorize derivatives within the asset class of the underlying instrument, though they are often considered an asset class of their own due to their unique characteristics.

Derivatives are versatile and serve several purposes, such as hedging risks, speculating on price movements, or leveraging positions. Common types of derivatives include futures, options, swaps, and forwards, each offering different structures and risk profiles. For example, a company might use derivatives to hedge against fluctuations in interest rates or commodity prices, while a trader might use options to speculate on the price of a stock.

1.4.4. Foreign Exchange (FX)#

The foreign exchange (FX) market is a critical component of the global financial system, where participants trade currencies. Transactions in the FX market are generally categorized as either spot or derivative transactions.

  • Spot transactions involve the immediate exchange of currencies, typically settling within two business days. While FX spot transactions are essential for international trade and finance, they are not classified as financial instruments under MiFID II, as they do not involve contractual obligations extending beyond the settlement period.

  • FX derivatives, such as forwards, options, and swaps, are used to hedge currency risk or speculate on currency movements. Unlike spot transactions, these contracts involve specific obligations between parties and are therefore considered financial instruments.

FX markets are used by a wide range of participants, including central banks (to manage currency reserves), corporations (to hedge currency risk in international operations), and investors looking to profit from currency fluctuations.

1.4.5. Commodities#

Commodities are physical goods such as oil, gold, and agricultural products, traded primarily in spot markets. These goods themselves are not considered financial instruments, as they represent tangible assets rather than financial claims. However, the derivatives based on commodities, such as futures and options on commodities, are classified as financial instruments. These contracts enable investors to gain exposure to commodity price movements without needing to take physical delivery of the underlying goods, providing opportunities for hedging and speculation.

1.4.6. Cryptocurrencies#

Cryptocurrencies, such as Bitcoin and Ethereum, are a relatively new and rapidly evolving asset class. Unlike traditional financial instruments, cryptocurrencies do not represent contractual obligations or financial claims. Instead, they function as digital assets, leveraging blockchain technology to provide decentralized and transparent transactions. Their value is driven by supply and demand dynamics, making them highly volatile compared to other asset classes.

Although cryptocurrencies themselves are not classified as financial instruments under existing regulatory frameworks, derivatives on cryptocurrencies (such as Bitcoin futures) are considered financial contracts. These derivatives allow market participants to speculate on or hedge against the price movements of cryptocurrencies, much like they would with other asset classes.

1.5. Financial Market Structures#

Market structures play a critical role in the functioning of financial markets, influencing how participants interact and how trades are executed. Traditionally, markets have been organized to accommodate the needs of intermediaries, such as dealers, who facilitate trading by providing liquidity. However, market structures have evolved significantly, shaped by technology, competition, and regulatory changes.

Financial markets can broadly be categorized into three main structures based on the role of intermediaries and the nature of participation:

Inter-Dealer Markets: Inter-dealer markets are venues where intermediaries, often referred to as dealers or market makers, trade exclusively with each other. The primary purpose of these markets is to allow dealers to manage their inventories effectively, enabling them to better serve their clients in dealer-to-client markets. The main types of inter-dealer markets are exchanges and inter-dealer broker networks. Notice that, while traditionally exclusive to dealers, some inter-dealer markets now allow institutional investors to participate directly through membership or other access arrangements, called Direct Market Access (DMA)

Dealer-to-Client Markets: Dealer-to-client markets are the most common venues where intermediaries interact with investors, including institutional and retail clients. Here, dealers act as liquidity providers, offering quotes to clients who wish to buy or sell financial instruments. These markets are typically either quote-driven, where prices are determined by dealers, or order-driven, where buyers and sellers are matched directly. Increasingly, electronic platforms have replaced traditional voice-based trading, improving efficiency and transparency.

Alternative Markets: Alternative markets represent a significant departure from traditional market structures by eliminating the segmentation between dealers and clients. These markets are often referred to as “all-to-all” trading platforms because they allow any participant—dealer or client—to interact and trade under the same conditions. Alternative markets have gained prominence due to technological advancements and regulatory pressures aimed at increasing competition and reducing trading costs. These markets often provide a mix of trading mechanisms, such as order books or dark pools, that facilitate liquidity without relying exclusively on dealers.

1.5.1. The Evolution of Market Structures#

Market structures have evolved through several stages, driven by the interplay of standardization, technological progress, competition, and regulation:

Single-Dealer to Client: Initially, trading was dominated by single-dealer platforms, where clients could only trade directly with one intermediary. These structures were common in the early stages of market development or for niche and complex products.

Multi-Dealer to Client: As markets matured, competition among dealers increased, leading to platforms that allowed clients to interact with multiple dealers simultaneously. This structure enhanced price transparency and liquidity for investors.

Dealer-to-Dealer Markets: The rise of inter-dealer markets enabled dealers to manage their inventories more effectively, creating a robust secondary layer of liquidity. Over time, some of these markets allowed direct access to clients through mechanisms like direct market access (DMA).

All-to-All Markets: Recent regulatory reforms, such as MiFID II in Europe and Reg NMS in the USA, have encouraged the development of all-to-all markets. These structures aim to lower trading costs by eliminating intermediary fees and creating a more level playing field for all participants.

1.5.3. Market structure according to specific regulations#

Different regulations have introduced specific terminology to describe market structures, providing their own classification of market structures.

In the US, regulation distinguishes between Exchange trading venues and Alternative Trading Systems (ATS), the latter grouping all non-exchange trading venues like ECNs, IDBs and Dark Pools. Dodd-Frank also introduces the concept of Swap Execution Facilities (SEF) as a trading platform to execute standardized derivatives, particularly swaps, ensuring pre-trade and post-trade transparency, efficiency and regulatory compliance.

In Europe, MiFID II four types of market structure are defined:

  • Regulated Markets: which can be mapped to exchanges

  • Multilateral Trading Facilities (MTFs): similar to ATS in the USA regulation, e.g. covering non-exchange trading venues like ECNs and dark pools. European regulation also introduces the concept of Organized Trading Facilities (OTFs), restricted to non-equities instruments and with more lax requirements, but in terms of structure is similar to MTFs.

  • Systematic Internalizers (SIs): not strictly a market structure, when a broker or dealer executes orders on own account outside of RMs, MTFs or OTFs.

1.6. The main building blocks of financial market structure#

1.6.1. Exchanges#

Exchanges (also known are regulated markets) are among the oldest institutions in financial markets, serving as centralized venues where buyers and sellers meet to trade financial instruments. They provide a structured environment for trading, ensuring transparency, fairness, and efficiency in the execution of transactions. Historically, exchanges were physical locations where traders gathered to negotiate prices through verbal communication and hand signals. Over time, these systems evolved into highly sophisticated electronic platforms that now dominate the financial landscape.

The primary role of an exchange is to facilitate the matching of buy and sell orders, ensuring that trades are executed efficiently and at market-driven prices. This process of price discovery is one of the most critical functions of an exchange. By aggregating supply and demand, exchanges reflect the collective valuation of financial instruments, providing a transparent benchmark for investors. This transparency extends to the dissemination of information, as exchanges publicly display orders and executed trades, enhancing market confidence and reducing information asymmetry among participants.

Another key function of exchanges is their contribution to liquidity. By concentrating a large number of buyers and sellers in a single venue, exchanges enable market participants to trade efficiently, minimizing the costs and delays associated with finding counterparties. For many financial instruments, the presence of a liquid exchange can mean the difference between a vibrant market and one that is illiquid and inaccessible.

Access to exchanges has traditionally been restricted to members, such as brokers and dealers, who execute trades on behalf of their clients or for their own accounts. However, with the advent of direct market access (DMA), institutional investors can now connect to exchanges directly using broker-provided infrastructure. This shift has allowed greater participation and has reduced the reliance on intermediaries, further increasing efficiency.

Over the years, exchanges have adapted to changing technologies and regulatory environments. The open-outcry systems of the past, where trading occurred on physical floors, have been largely replaced by electronic order books. These systems enable the seamless matching of orders, often in milliseconds, and ensure that market activity is highly transparent. Despite these advancements, the core purpose of exchanges—to facilitate fair and efficient trading—has remained unchanged.

Exchanges cater to a wide range of asset classes, including equities, fixed income, and derivatives. In the equities market, prominent exchanges such as the New York Stock Exchange (NYSE) and NASDAQ in the United States, and the London Stock Exchange (LSE) and Deutsche Börse in Europe, dominate. In the derivatives market, institutions like the Chicago Mercantile Exchange (CME) and Eurex play a similar role, providing venues for trading standardized contracts. The evolution of exchanges has also seen them diversify their offerings, with many now facilitating the trading of newer instruments like exchange-traded funds (ETFs) and cryptocurrencies.

While exchanges offer many advantages, including transparency, reduced counterparty risk, and high efficiency, they face increasing competition from alternative trading systems. These include dark pools and electronic communication networks, which operate outside traditional exchange frameworks. Regulatory reforms, such as MiFID II in Europe and Reg NMS in the United States, have intensified this competition by encouraging the creation of private trading venues that rival exchanges in functionality.

Despite these challenges, exchanges continue to be a cornerstone of financial markets. Their ability to adapt to technological advancements and regulatory shifts ensures their relevance in an ever-changing landscape. By providing a centralized and regulated platform for trading, exchanges remain indispensable for fostering market confidence and maintaining the integrity of financial systems.

1.6.2. Inter-Dealer Broker Networks (IDBs)#

Inter-dealer broker (IDB) networks play a crucial role in financial markets by acting as intermediaries between dealers, facilitating transactions that would otherwise be difficult to execute directly. These networks are particularly important in over-the-counter (OTC) markets, where trading is less centralized and often involves complex, less standardized financial instruments.

Unlike exchanges, which are open to a wide range of participants, inter-dealer broker networks operate exclusively within the realm of dealers, such as banks and other financial institutions that act as market makers. These networks exist to bridge gaps in supply and demand among dealers, ensuring that liquidity remains available even in the most challenging market conditions. They provide a venue for dealers to manage inventory imbalances, hedge positions, and execute large trades without disrupting the broader market.

Historically, inter-dealer broker networks relied heavily on voice-based trading, where brokers would connect dealers over the phone to negotiate trades. This method was particularly suited to illiquid or bespoke instruments, where the nuances of each deal required direct human interaction. However, the rise of electronic trading has transformed these networks, with many now offering electronic platforms that support faster and more efficient trade execution. These platforms often aggregate quotes from multiple dealers or, in some cases, provide fully functional order books similar to those found on exchanges. For highly liquid instruments, such as government bonds or certain derivatives, electronic trading has become the dominant mechanism within inter-dealer networks.

The services provided by inter-dealer brokers extend beyond mere trade execution. They act as neutral intermediaries, ensuring that transactions remain anonymous to prevent sensitive information about trading strategies or inventory levels from leaking to competitors. This anonymity is a key feature of inter-dealer broker networks, particularly in markets where large trades can significantly impact prices.

Inter-dealer broker networks are especially vital in markets that are predominantly OTC, such as fixed income, foreign exchange, and derivatives. For example, platforms like BrokerTec and MTS Cash are central to the trading of government and corporate bonds, while ICAP and CME SwapStream dominate in the trading of swaps. In the foreign exchange market, inter-dealer platforms like EBS aggregate liquidity and facilitate price discovery across major currency pairs.

In recent years, regulatory changes and technological advancements have reshaped the inter-dealer broker landscape. Regulations such as MiFID II and Dodd-Frank have introduced new transparency and reporting requirements, pushing brokers to modernize their operations and adopt electronic trading systems. These changes have enhanced efficiency but also increased competition among brokers and other trading venues. At the same time, some inter-dealer networks have begun offering limited access to institutional investors through mechanisms like direct market access (DMA), further blurring the lines between traditional inter-dealer and dealer-to-client markets.

Despite these shifts, inter-dealer broker networks remain a cornerstone of financial markets, providing critical infrastructure for OTC trading. They ensure that dealers can manage risk, adjust positions, and execute large trades without destabilizing markets. As technology continues to advance, these networks are likely to evolve further, integrating new tools to enhance their efficiency and adaptability while continuing to fulfill their essential role in the financial system.

1.6.3. Electronic Communication Networks (ECNs)#

Electronic Communication Networks (ECNs) are digital platforms that connect buyers and sellers directly, providing a decentralized and efficient mechanism for trading financial instruments. As traditional exchanges have become electronic trading venues, the differences between them and ECNs is blurring. Both of them typically operate as “lit” platforms, based on order books that are fully transparent, offering real-time insights into market depth and pricing. The main differences are essentially:

  • the role of intermediaries like brokers or dealers, who have a monopoly of access and a dominant role as market-makers in exchanges

  • that exchanges are still considered the official pricing references for financial instruments, used for end of day valuations of inventories and settlement of contracts.

For those asset classes, like FX, where traditional exchanges don’t exist, ECNs have a prominent role. Examples are ECNs like FXAll, Hotspot FX and 360T. A similar situation happens for Crypto, which as a relatively new asset class, does not trade in traditional exchanges and has also adopted ECN-like models. Platforms such as Binance and Coinbase Pro operate as order-driven trading venues, offering functionality similar to standard ECNs but tailored to the unique dynamics of digital assets.

Thanks to innovative trading functionalities and competitive fees, ECNs are also becoming more relevant for financial instruments mostly traded in exchanges. In the equity markets, Turquoise, a pan-european ECN, provides efficient trading across multiple equity markets, while CBOE (formerly BATS) has grown to become one of the largest equity trading platforms in the world.

In fixed income, ECNs such as BrokerTec and MarketAxess have introduced new efficiencies. BrokerTec specializes in government bond trading and repos, while MarketAxess focuses on corporate bonds, integrating both ECN functionality and Request-for-Quote (RfQ) systems. These platforms enable dealers and institutional investors to trade with greater speed and transparency in traditionally opaque markets.

Despite their many benefits, ECNs face challenges, including market fragmentation and regulatory scrutiny. As multiple ECNs compete for liquidity, market participants often need to navigate between venues to find the best prices. Regulations like MiFID II in Europe and Reg NMS in the United States have introduced transparency and operational requirements that ECNs must comply with, adding complexity to their operations. Additionally, the technological demands of maintaining ultra-low latency systems make ECNs resource-intensive to operate.

Nevertheless, ECNs have fundamentally reshaped financial markets by increasing accessibility, reducing transaction costs, and fostering competition. They have become a cornerstone of modern trading, offering a blend of transparency, efficiency, and innovation. As markets evolve, ECNs will likely continue to expand their reach, further blurring the lines between traditional and alternative trading venues.

1.6.4. Dark Pools#

Dark pools are private trading venues where buy and sell orders are matched without being publicly displayed. These platforms operate outside traditional exchanges and are designed to provide anonymity and minimize market impact, particularly for large trades. Dark pools have become an essential part of the financial ecosystem, catering primarily to institutional investors who seek to execute sizable orders without revealing their intentions to the broader market.

The key feature of dark pools is their opacity. Unlike lit markets, where order books are visible to all participants, dark pools conceal order details until after a trade is executed. This anonymity helps mitigate the risk of adverse price movements, which can occur when other market participants detect large orders and trade against them. For institutional investors, this reduces execution costs and enables more efficient handling of large positions.

Dark pools emerged as a response to the limitations of traditional exchanges, particularly for block trading. As markets became more fragmented and lit venues introduced greater transparency requirements, the demand for private trading mechanisms grew. Today, dark pools are operated by a variety of entities, including investment banks, brokerage firms, and even exchanges themselves. Prominent examples include Credit Suisse Crossfinder, ITG POSIT, and Liquidnet, which cater to equity markets, and Hotspot QT, which offers dark liquidity for foreign exchange trading.

In terms of functionality, dark pools typically use one of three matching mechanisms:

Dark Order Books: These pools match hidden limit orders based on price and time priority.

Midpoint Matching: Some dark pools use the midpoint of the bid and ask prices from a lit market as a reference price for matching trades.

Pass-Through Mechanisms: Unmatched orders in dark pools may be routed to lit markets for execution.

Dark pools are most prevalent in equity markets, where they account for a significant portion of trading volume in major financial centers. However, their influence has also expanded into other asset classes, including foreign exchange and fixed income. For example, platforms like Liquidnet and Crossfinder are frequently used by institutional investors to execute large equity trades, while Hotspot QT caters to FX transactions.

Despite their advantages, dark pools have attracted scrutiny from regulators and market participants. Critics argue that the lack of transparency can lead to unfair trading practices and reduce the quality of price discovery in lit markets. In response, regulatory initiatives like MiFID II in Europe have introduced stricter oversight and reporting requirements for dark pool activity. In the United States, similar efforts under the SEC aim to ensure that dark pools operate fairly and do not disadvantage other market participants.

Technological advancements have also shaped the evolution of dark pools. Many now integrate advanced algorithms and smart order routing systems to optimize trade execution. These tools analyze market conditions across lit and dark venues to determine the best execution strategy for a given order.

In summary, dark pools play a critical role in modern financial markets, providing a valuable tool for institutional investors to execute large trades with minimal market impact. While they continue to face challenges related to transparency and regulation, their importance in facilitating efficient and discreet trading ensures they remain a key component of the trading landscape.

1.6.5. Systematic Internalizers#

A Systematic Internalizer is an investment firm that executes client orders internally, using its own capital, rather than routing those orders to external trading venues like exchanges or Multilateral Trading Facilities (MTFs). Unlike traditional trading venues, SIs do not operate a central order book where multiple participants interact; instead, they provide quotes bilaterally to their clients.

The traditional role of an SI has been handling smaller, less liquid trades or the provision of tailored liquidity for institutional clients. By internalizing trades, they reduce reliance on external venues and offer greater control over execution. This mechanism ensures tighter spreads, faster execution, and potentially better pricing, making them attractive to sophisticated market participants.

In recent years a new breed of systematic internalizers have emerged as dominant players in the financial markets. They are the so-called new liquidity providers, non-bank firms with a strong focus on technology and automation, most of them having started as High-Frequency-Trading (HFT) firms. Examples of these firms are Citadel Securities and Virtu Financial. These firms operate as traditional market-makers in lit trading venues, but as SIs they have been instrumental in the execution of retail orders routed by online brokers like Robinhood. For them, retail orders provide a relatively noisy flow that can be matched internally without routing it to trading venues, providing relevant savings in fees and spreads that can be passed partially to the online brokers. Such trading model is known as payment for order flow (PFOF) Those, in turn, can offer commission-free trading to retail investors, cannibalizing traditional brokers that route orders to trading venues.

The dominance of firms like Citadel and their role in platforms such as Robinhood has drawn regulatory attention. Critics argue that PFOF and internalization may create potential conflicts of interest and reduce transparency compared to lit markets.

1.7. Overview of market structures per asset class#

1.7.1. Equity market structure#

The equity market structure represents the intricate framework through which stocks and other equity instruments are traded. It has undergone a profound transformation over the years, influenced by technological advancements, regulatory reforms, and the diversification of trading venues. Modern equity markets are characterized by a blend of traditional exchanges, alternative trading systems, and off-exchange mechanisms, all working together to facilitate liquidity, price discovery, and trade execution.

Traditional Exchanges

At the heart of the equity market structure are traditional exchanges such as the New York Stock Exchange (NYSE), NASDAQ, London Stock Exchange (LSE), and Deutsche Börse. These venues provide centralized platforms for trading shares of publicly listed companies. Historically, exchanges were physical locations where traders met to negotiate prices through open-outcry systems. Today, most trading occurs electronically, with Central Limit Order Books (CLOBs) being the dominant mechanism. CLOBs match buy and sell orders based on price and time priority, ensuring transparent and efficient execution. Exchanges play a critical role in price discovery by reflecting the collective views of market participants and aggregating supply and demand. They also provide regulatory oversight to ensure fairness and investor protection.

The Rise of Alternative Trading Systems

In recent years, the dominance of traditional exchanges has been challenged by the rise of Alternative Trading Systems (ATSs). These include Electronic Communication Networks (ECNs) and dark pools, which offer innovative alternatives for trade execution. As we have discussed above, ECNs are fully electronic platforms that match orders directly between participants, bypassing intermediaries. They are especially effective for high-frequency and algorithmic trading, where speed and tight spreads are essential. Dark pools, on the other hand, cater to institutional investors seeking anonymity when executing large trades. By concealing order details, dark pools minimize the market impact of block trades, helping reduce transaction costs. Prominent examples of dark pools operating in the Equity markets include Liquidnet and Credit Suisse Crossfinder, while ECNs like Instinet and BATS (now part of CBOE) have become critical to equity trading infrastructure.

The Growth of Off-Exchange Trading: Systematic internalizers

As we discussed previously, another significant development particularly relevant for the equity market structure is the growth of off-exchange trading. Internalization and wholesale market making have become dominant forces, driven by firms like Citadel Securities and Virtu Financial. These firms match buy and sell orders internally or execute them against their own inventories. This approach offers several advantages, including cost efficiency, faster execution, and price improvements for retail investors. Retail trading platforms like Robinhood rely heavily on these wholesale market makers, routing customer orders to them for execution. While this model democratizes access to equity markets, it has also sparked regulatory debates about transparency and potential conflicts of interest, particularly regarding payment for order flow (PFOF).

The Role of Regulation

The regulatory landscape has played a pivotal role in shaping equity market structures. In the United States, Regulation National Market System (Reg NMS), introduced in 2005, prioritizes best execution by requiring trades to be executed at the best available price across all venues. This regulation has fostered competition and innovation, but it has also contributed to market fragmentation. In Europe, the Markets in Financial Instruments Directive II (MiFID II) has brought stricter transparency requirements, mandating both pre-trade and post-trade reporting for equities. MiFID II also introduced volume caps on dark pool trading to preserve price discovery in lit markets while encouraging competition through Multilateral Trading Facilities (MTFs).

Opportunities and Challenges

The evolution of equity markets has brought both opportunities and challenges. Market fragmentation, driven by the proliferation of trading venues, has increased the complexity of accessing consolidated liquidity. The rise of algorithmic and high-frequency trading has revolutionized how equities are traded, emphasizing speed and efficiency, but it has also raised concerns about market stability during volatile periods. Additionally, the surge in retail investor participation, facilitated by platforms like Robinhood, has changed market dynamics, increasing reliance on internalizers and raising questions about fairness.

Despite these challenges, equity markets remain a cornerstone of the global financial system, adapting to technological advancements and regulatory changes while continuing to serve the needs of a diverse range of participants. Balancing competition, transparency, and efficiency will be essential as market structures evolve further in response to new innovations and global economic trends.

1.7.2. Fixed income market structure#

The fixed income market, which encompasses government bonds, corporate bonds, and other debt instruments, plays a central role in the global financial system. It provides a mechanism for governments, corporations, and institutions to raise capital through borrowing while offering investors a source of steady income and portfolio diversification. Unlike equity markets, the fixed income market is primarily over-the-counter (OTC) in nature, meaning that trades are negotiated bilaterally between participants rather than through centralized exchanges. This characteristic defines its structure, trading mechanisms, and the way liquidity is provided.

Market Segments

The segmentation between inter-dealer markets and dealer-to-client markets is particularly prominent in the fixed income market structure.

The inter-dealer market facilitates trading among dealers or market makers, allowing them to adjust their inventories and manage risk. These transactions often take place on specialized platforms such as BrokerTec and MTS, which cater to highly liquid instruments like government bonds. These platforms operate using Central Limit Order Books (CLOBs), where prices and order depths are visible to participants, ensuring transparency and efficient price discovery.

The dealer-to-client market, on the other hand, is where dealers interact directly with institutional investors such as asset managers, pension funds, and insurance companies. This segment is typically less transparent than the inter-dealer market, as prices and order flows are not widely disseminated. Instead, trading often occurs through Request-for-Quote (RfQ) systems, where clients request prices from multiple dealers before executing a trade. Platforms like Tradeweb, Bloomberg Terminal, and MarketAxess dominate this space, providing electronic solutions that streamline the negotiation process. In this market, liquidity is heavily dependent on the willingness of dealers to provide quotes, making it less consistent than in more standardized markets like equities or foreign exchange.

Liquidity and Instrument Types

Government bonds represent one of the most liquid segments of the fixed income market, with electronic trading accounting for more than 60-70% of activity at the beginning of the 2020s. These bonds are often traded in large volumes and benefit from a broad base of market participants, including central banks, hedge funds, and proprietary trading firms. Platforms like BrokerTec and Eurex Repo are central to the trading of government debt, offering robust infrastructure and high levels of transparency. Corporate bonds, by contrast, are less liquid, with electronic trading comprising only 30-40% of volume, primarily for smaller trades. Larger corporate bond trades, often referred to as block trades, are typically negotiated directly between counterparties or through specialized trading desks.

The Impact of Technology and Innovation

The evolution of technology and the rise of electronic trading have significantly influenced the fixed income market structure. While voice trading continues to play a role, particularly for bespoke or illiquid instruments, electronic platforms have gained prominence. These platforms not only improve efficiency and reduce transaction costs but also provide pre-trade and post-trade transparency. MarketAxess, for example, has pioneered innovations like Open Trading, a model that allows all-to-all trading, enabling any participant to act as a liquidity provider. This is a notable departure from the traditional dealer-centric model.

Non-bank liquidity providers, such as Citadel Securities and Virtu Financial, have also emerged as influential players in the fixed income market. These firms leverage advanced algorithms and high-frequency trading strategies to provide continuous two-way pricing, challenging the traditional dominance of bank dealers. Their presence has narrowed bid-ask spreads and improved execution quality for many instruments, though their focus often remains on the most liquid securities.

The Role of Regulation

Regulation has played a significant role in shaping the fixed income market structure, particularly in the wake of the 2008 financial crisis. In Europe, MiFID II introduced stringent transparency requirements, mandating pre-trade and post-trade reporting for bond transactions. As we discussed previously, this has increased the availability of market data via APAs, improving price discovery, but on the other hand it has imposed relevant compliance costs on market participants. In the United States, the Dodd-Frank Act emphasized centralized clearing and execution for fixed income derivatives, reducing counterparty risk and increasing oversight.

Challenges and Future Directions

Despite these advancements, the fixed income market continues to face challenges. Liquidity remains fragmented, particularly for less liquid instruments like high-yield bonds or municipal debt. The reliance on dealer-provided liquidity means that market conditions can deteriorate rapidly during periods of stress, as seen during the COVID-19 market dislocation in 2020. Moreover, the adoption of electronic trading, while growing, still lags behind other asset classes, reflecting the bespoke nature of many fixed income instruments.

1.7.3. FX market structure#

The foreign exchange (FX) market is the largest and most liquid financial market in the world, where currencies are traded across a decentralized global network. Unlike equity markets, the FX market lacks a central exchange and instead operates through a vast web of interconnected trading platforms, banks, and financial institutions. This decentralized structure allows the market to function continuously, 24 hours a day, across different time zones.

Market Segments

The FX market also exhibits a prominent segmentation between inter-dealer and dealer-to-client markets. In the inter-dealer market, major banks and liquidity providers trade currencies among themselves to balance their inventories and manage risk. This segment is characterized by high volumes and tight spreads, as participants consist of sophisticated institutions. Dealer-to-client markets, on the other hand, involve transactions between banks or liquidity providers and their clients, such as corporations, asset managers, or retail traders. Here, pricing is often less competitive, as it reflects the service costs of providing tailored liquidity to end users.

Trading in the FX market is facilitated by a mix of single-dealer platforms, multi-dealer platforms, and electronic communication networks (ECNs). Single-dealer platforms are proprietary systems operated by large banks, such as Citi’s Velocity and Deutsche Bank’s Autobahn. These platforms provide clients with direct access to streaming prices and customized liquidity. Multi-dealer platforms like Refinitiv FXall and 360T aggregate prices from multiple liquidity providers, enabling clients to compare quotes and execute trades more efficiently. ECNs, such as EBS (Electronic Brokerage System) and CBOE FX, serve as centralized hubs for inter-dealer trading. ECNs operate using an order-driven model, similar to a stock exchange, where participants can place and match orders anonymously, ensuring tight spreads and deep liquidity for major currency pairs like EUR/USD and USD/JPY.

Another important component of FX market structure is the over-the-counter (OTC) nature of most transactions. Unlike exchange-traded assets, FX trades are conducted bilaterally between counterparties, with terms negotiated directly. While this flexibility allows for customization, it also introduces risks such as counterparty default. To address these risks, central counterparties (CCPs) and clearinghouses have become increasingly important, particularly for FX derivatives, providing a level of security through post-trade clearing.

The Impact of Technology and Innovation

The rise of algorithmic trading has profoundly impacted the FX market. Algorithms now execute a significant portion of FX trades, particularly in the spot and forward markets. These systems are designed to optimize execution strategies, minimize market impact, and reduce transaction costs. High-frequency trading (HFT) firms, including non-bank liquidity providers like Citadel Securities and XTX Markets, have further transformed the landscape by injecting liquidity into the market and narrowing bid-ask spreads. These firms compete directly with traditional bank liquidity providers, challenging the conventional dominance of large financial institutions.

The Role of Regulation

Regulation has also played a key role in shaping FX market structure. In the United States, the Dodd-Frank Act introduced Swap Execution Facilities (SEFs) for certain FX derivatives, such as non-deliverable forwards (NDFs) and options. SEFs mandate pre-trade transparency and centralized execution, bringing these instruments closer to the regulatory framework of listed markets. In Europe, MiFID II has extended reporting requirements to FX transactions, increasing transparency and ensuring compliance across borders.

Challenges and Future Directions

Despite its decentralized nature, the FX market faces challenges, including market fragmentation and unequal access to liquidity. Retail traders, for instance, often face wider spreads and less favorable execution compared to institutional players. Platforms like eToro and retail aggregators provide retail access to FX trading but rely on intermediaries to bridge the gap between retail and institutional markets. Furthermore, regulatory scrutiny of practices like last look, where liquidity providers can reject trades even after quoting prices, has raised questions about fairness and execution quality.

1.7.4. Derivatives markets structure#

The derivatives market structure encompasses a wide range of trading venues and mechanisms that facilitate the buying and selling of financial instruments whose value is derived from underlying assets. These instruments, including futures, options, swaps, and credit derivatives, are critical tools for hedging risk, speculating on price movements, and enhancing portfolio efficiency. The structure of this market is complex, reflecting the diversity of its participants, instruments, and trading mechanisms.

Centralized and Decentralized Markets

Derivatives markets are divided into two primary categories: centralized markets, where standardized contracts are traded on regulated exchanges, and decentralized over-the-counter (OTC) markets, where bespoke contracts are negotiated directly between counterparties.

Centralized markets operate through exchanges like the Chicago Mercantile Exchange (CME), Eurex, and the Intercontinental Exchange (ICE). These venues provide a transparent and regulated environment for trading standardized derivatives, such as futures and options. Exchanges use Central Limit Order Books (CLOBs) to match buy and sell orders, ensuring efficient price discovery and liquidity. Additionally, centralized clearinghouses guarantee the performance of contracts, mitigating counterparty risk and enhancing market stability.

In contrast, OTC markets are decentralized networks where parties negotiate derivative contracts directly. OTC derivatives, including swaps and bespoke options, offer flexibility in terms of contract size, duration, and underlying asset. This customization makes OTC markets essential for addressing specific hedging or investment needs, especially for large institutional players. However, the bilateral nature of OTC trading introduces counterparty risk and limits transparency.

Product Segmentation

The derivatives market is further categorized by the instruments traded and the venues where they are exchanged:

  • Futures and Options Markets: Futures and options are predominantly traded on exchanges due to their standardized nature. Venues like CME, Eurex, and the London International Financial Futures Exchange (LIFFE) dominate this segment. These contracts provide liquidity and leverage for speculating on asset price movements or managing exposure to commodities, interest rates, or currencies.

  • Swap Markets: Swaps, such as interest rate swaps (IRS) and cross-currency swaps, are primarily traded in OTC markets. Platforms like ICAP i-Swap, Tradeweb, and CME SwapStream have modernized this segment, introducing electronic trading and central clearing. In the United States, the Dodd-Frank Act established Swap Execution Facilities (SEFs) to increase transparency and centralize trading for standardized swap contracts.

  • Credit Derivatives: Credit derivatives, including CDS, allow market participants to hedge or speculate on credit risk. These instruments are traded OTC but are increasingly cleared through centralized clearinghouses like ICE Clear Credit to reduce systemic risk.

Recent developments

In recent years, non-bank liquidity providers, such as Citadel Securities and Virtu Financial, have become critical players in derivatives markets. These firms use advanced algorithms and high-frequency trading systems to provide continuous liquidity, particularly in standardized instruments like futures and options. Their presence has narrowed bid-ask spreads, enhanced price discovery, and reduced transaction costs for participants. However, their influence remains limited in bespoke OTC markets, where traditional dealers and institutional clients dominate.

Technological advancements have significantly transformed derivatives markets, particularly in electronic trading and post-trade processes. Exchanges and OTC platforms alike have adopted advanced algorithms and smart order routing systems to optimize execution. Central clearinghouses now integrate with trading platforms to streamline settlement processes, reducing operational risk.

The rise of algorithmic trading has been especially pronounced in liquid derivatives markets like futures. High-frequency traders (HFTs) dominate these segments, leveraging speed and computational power to capture small price inefficiencies. This shift has improved market efficiency but has also introduced new challenges, including concerns about flash crashes and the impact of HFT on market stability.

Regulation and Market Evolution

The derivatives market structure has been heavily influenced by regulatory reforms, particularly following the 2008 financial crisis. In the United States, the Dodd-Frank Act introduced sweeping changes, requiring standardized OTC derivatives to be traded on SEFs and cleared through central counterparties. In Europe, MiFID II extended pre-trade and post-trade transparency requirements to derivatives markets and introduced Organized Trading Facilities (OTFs) to regulate non-equity instruments.

These regulations aim to reduce systemic risk by increasing transparency and centralizing trading activity. However, they have also introduced challenges, including higher compliance costs and reduced flexibility for bespoke trading.

Challenges and Trends

As it happens to other asset classes, the derivatives market faces ongoing challenges. Liquidity fragmentation between exchanges and OTC venues can complicate execution, particularly for large or complex trades. The reliance on traditional dealers in OTC markets also means that liquidity may become constrained during periods of market stress.

Emerging trends, such as the tokenization of derivatives and the integration of blockchain technology, are expected to reshape market structures further. These innovations promise greater efficiency, transparency, and accessibility, potentially bridging the gap between centralized and decentralized trading models.

1.7.5. Crypto market structure#

The cryptocurrency market structure represents a unique and rapidly evolving framework for trading digital assets such as Bitcoin, Ethereum, and numerous other cryptocurrencies. Unlike traditional financial markets, the crypto market operates on a decentralized foundation, with trading and transactions facilitated by blockchain technology. This distinct characteristic has led to the development of innovative trading venues and mechanisms, catering to a wide range of participants, from retail investors to institutional traders.

Centralized Exchanges (CEXs)

Centralized exchanges are the cornerstone of the crypto market, providing a familiar and accessible platform for buying, selling, and trading digital assets. These exchanges operate similarly to traditional stock exchanges but with a focus on cryptocurrencies. They serve as intermediaries, matching buyers and sellers while maintaining custody of users’ assets in their wallets.

Prominent examples of centralized exchanges include Binance, Coinbase, Kraken, and Bitfinex. These platforms offer a wide range of trading services, including spot trading, futures and options trading, and margin trading. They typically use order books to match buy and sell orders, providing transparent pricing and liquidity. However, centralized exchanges are also custodial, meaning they control users’ private keys, raising concerns about security and regulatory compliance.

CEXs dominate the crypto trading landscape due to their ease of use, high liquidity, and comprehensive trading tools. Institutional investors often prefer these platforms because they offer robust infrastructure, regulatory oversight in some jurisdictions, and access to advanced trading features like API connectivity for algorithmic trading.

Decentralized Exchanges (DEXs)

Decentralized exchanges represent an innovative alternative to centralized platforms, leveraging blockchain technology to enable peer-to-peer trading without intermediaries. Unlike CEXs, DEXs operate non-custodially, meaning users retain full control of their private keys and assets throughout the trading process. Transactions on DEXs are executed via smart contracts, ensuring transparency and automation.

Examples of popular DEXs include Uniswap, SushiSwap, and PancakeSwap, which primarily operate on Ethereum and Binance Smart Chain (BSC). These exchanges use automated market-making (AMM) models, where liquidity is provided by users who deposit assets into liquidity pools. Prices are determined algorithmically based on the ratio of assets in the pool. While DEXs offer unparalleled decentralization and security, they often suffer from lower liquidity, slower execution times, and higher transaction fees during network congestion.

Hybrid Models

Some platforms, like dYdX and Binance DEX, combine features of both centralized and decentralized exchanges. These hybrid models aim to balance the transparency and user control of DEXs with the speed and efficiency of CEXs. For instance, dYdX offers non-custodial trading for derivatives while maintaining centralized order matching for performance.

Over-the-Counter (OTC) Desks and Institutional Services

For large-scale transactions, over-the-counter (OTC) desks have become a critical component of the crypto market structure. These venues facilitate private trades between buyers and sellers, bypassing public order books to avoid slippage and market impact. OTC services are particularly popular among institutional investors, hedge funds, and high-net-worth individuals.

Major players in the OTC space include Genesis Trading, Cumberland DRW, and Kraken OTC. These desks provide tailored services, including deep liquidity, anonymity, and support for large transactions in less liquid altcoins.

Crypto Derivatives

The derivatives market for cryptocurrencies has grown rapidly, providing traders with tools to hedge risk, speculate on price movements, and manage exposure. Platforms like Binance Futures, CME Group, FTX (before its collapse), and Deribit offer a wide range of products, including futures, options, and perpetual contracts. These platforms cater to sophisticated traders and institutions by offering leverage, advanced analytics, and liquidity for a variety of instruments.

The integration of traditional financial institutions, such as CME Group offering Bitcoin and Ethereum futures, highlights the increasing institutionalization of the crypto derivatives market.

Regulation and Challenges

The regulatory environment for cryptocurrencies remains fragmented and uncertain. While some jurisdictions, like the United States and Europe, have introduced frameworks to govern crypto trading, many regions still lack comprehensive regulation. Key challenges include:

  • Compliance: Centralized exchanges face increasing scrutiny regarding anti-money laundering (AML) and know-your-customer (KYC) requirements. Compliance standards that are taken for granted in traditional financial markets are not ensured in crypto markets, giving raise to recent scandals like the unauthorized use of customer funds by the now bankrupted FTX crypto exchange to provide liquidity to Alameda, a crypto investment firm that was also owned by the CEO of FTX.

  • Security: Both centralized and decentralized platforms have been targets of hacks and exploits, raising concerns about asset protection.

  • Market Manipulation: The lack of consistent oversight has led to concerns about wash trading, pump-and-dump schemes, and other forms of market manipulation.

Emerging Trends

The crypto market structure continues to evolve, driven by technological advancements and shifting participant needs. Key trends include:

  • Decentralized Finance (DeFi): Beyond trading, DeFi protocols enable lending, borrowing, and yield farming, expanding the role of decentralized exchanges.

  • Institutional Adoption: The entry of major financial institutions, such as BlackRock and Fidelity, into the crypto space is increasing the demand for regulated trading venues and custody solutions.

  • Tokenized Assets: The tokenization of traditional assets, such as equities and real estate, is creating new opportunities for trading on blockchain-based platforms.

  • Layer 2 Solutions: To address scalability issues, Layer 2 technologies like Optimism and Arbitrum are reducing transaction costs and improving execution times for DEXs.

1.8. Regulation of financial markets#

The regulation of financial markets is a cornerstone of global economic stability, designed to ensure transparency, fairness, and the protection of market participants. Financial market regulation governs the activities of trading venues, intermediaries, and participants, shaping how capital flows and risks are managed. It evolves constantly in response to technological advancements, market innovation, and crises that reveal vulnerabilities in the system.

Objectives of Financial Market Regulation

The primary objectives of financial market regulation are:

  • Ensuring Market Integrity: Regulations are designed to prevent fraud, manipulation, and insider trading. By safeguarding fair practices, regulators maintain investor confidence.

  • Protecting Investors: Retail and institutional investors are protected through rules governing disclosure, risk assessment, and the fiduciary responsibilities of financial intermediaries.

  • Promoting Transparency: Pre-trade and post-trade transparency requirements ensure that all participants have access to accurate and timely information about market activity.

  • Mitigating Systemic Risk: Regulations aim to prevent systemic crises by requiring risk management practices, such as capital adequacy, margin requirements, and stress testing. Fostering Competition: Regulatory frameworks often promote competition by allowing new entrants and innovations, such as alternative trading systems, while curbing anti-competitive behavior.

Key Regulatory Frameworks

Financial markets operate under a wide variety of regulatory regimes, with significant differences across jurisdictions. The following are key frameworks that define modern market regulation:

In the United States, two major regulatory frameworks define the structure of financial markets:

  • The Regulation National Market System (Reg NMS) focuses on equities, aiming to ensure best execution and fair access to trading venues. By encouraging competition between exchanges and alternative trading systems (ATSs), Reg NMS has fostered innovation but also contributed to market fragmentation as liquidity is spread across numerous venues.

  • The Dodd-Frank Wall Street Reform and Consumer Protection Act, enacted after the 2008 financial crisis, seeks to reduce systemic risk and enhance transparency in derivatives markets. Among its key contributions is the introduction of Swap Execution Facilities (SEFs), which standardize derivatives trading through centralized clearing and reporting. Additionally, Dodd-Frank strengthens consumer protections by imposing stricter oversight on complex financial products.

In Europe, the regulatory landscape is shaped by the Markets in Financial Instruments Directive II (MiFID II) and the European Market Infrastructure Regulation (EMIR):

  • MiFID II provides a comprehensive framework governing equities, fixed income, derivatives, and other instruments. It imposes stringent pre-trade and post-trade transparency requirements across asset classes and defines distinct market structures, including Multilateral Trading Facilities (MTFs), Organized Trading Facilities (OTFs), and Systematic Internalizers (SIs). To preserve price discovery, MiFID II also limits dark pool trading with volume caps, while allowing exemptions for large-in-scale orders.

  • Meanwhile, EMIR addresses derivatives markets by mandating central clearing for standardized contracts and enhancing reporting requirements. These measures aim to reduce counterparty risk and improve oversight of derivative transactions.

At a global level, several initiatives play a critical role in harmonizing financial market regulations:

  • The Basel III Framework focuses on international banking standards, enhancing capital adequacy, leverage ratios, and liquidity coverage to bolster financial stability.

  • The International Organization of Securities Commissions (IOSCO) establishes global benchmarks for securities market regulation, fostering international cooperation to tackle cross-border challenges effectively.

Challenges in Financial Market Regulation

Despite its critical importance, regulating financial markets is fraught with challenges. The rapid pace of technological innovation often outpaces regulatory frameworks, as seen with the rise of high-frequency trading (HFT) and cryptocurrencies. Ensuring that rules remain effective without stifling innovation requires a delicate balance.

Market globalization introduces additional complexity. Cross-border trading, global derivatives markets, and international capital flows necessitate coordination between regulators. However, jurisdictional differences often lead to regulatory arbitrage, where firms exploit inconsistencies to minimize compliance costs.

Recent Developments and Trends

  • Regulating Emerging Technologies: Electronic and Algorithmic Trading were among the first major technological advances disrupting the workings of financial markets. Their regulation has been addressed by sections of the USA and European frameworks mentioned above. In particular, the most comprehensive regulation of Algorithmic Trading has been tackled by a specific section of MiFID 2, RTS-6, as we will discuss in the specific chapter introducing this technology. More recently, the rise of cryptocurrencies and decentralized finance (DeFi) has prompted new regulatory efforts. Jurisdictions like the European Union are leading with frameworks such as the Markets in Crypto-Assets Regulation (MiCA), while others, like the United States, are still defining comprehensive policies. Artificial Intelligence, particularly the use of Large Language Models (LLMs) and agent-based frameworks for trading, is expected to be the next major chapter of regulatory oversight.

  • Environmental, Social, and Governance (ESG) Regulation: As sustainable investing gains traction, regulators are focusing on mandating ESG disclosures and preventing green-washing. Europe’s Sustainable Finance Disclosure Regulation (SFDR) is a leading example.

  • Data and Cybersecurity: The reliance on digital platforms and cloud-based systems has increased regulatory focus on data protection, cybersecurity, and operational resilience. Here, specific regulatory frameworks like the European Union’s General Data Protection Regulation (GDPR) also have an impact in the financial markets.

  • Retail Investor Protection: The surge in retail trading, driven by platforms like Robinhood, is prompting new rules on transparency, execution quality, and the specific regulation of practices like payment for order flow (PFOF).