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Market-Maker Controversies

Market makers occupy a paradoxical position in modern finance: they provide essential liquidity that enables trading but operate under business models that create inherent conflicts of interest. Over the past two decades, regulatory scrutiny has intensified as controversies have revealed how profit motives can sometimes override market fairness and transparency. Understanding these controversies is critical for investors who want to grasp how markets actually function and where risks emerge.

Quick definition​

Market-maker controversies refer to the systemic and episodic conflicts, disputes, and ethical challenges arising from market makers' dual role as both liquidity providers and profit-seeking firms. These include payment-for-order-flow arrangements, preferential pricing for certain clients, potential manipulation tactics, and the structural risks they create during market stress events.

Key takeaways​

  • Conflicts of interest are structural: Market makers profit from spreads and often receive incentives to route orders through particular venues, creating tension between their duty to provide fair execution and their profit motive.
  • Payment for order flow remains contentious: The practice of brokers selling retail order flow to market makers raises questions about whether retail investors receive the best execution prices.
  • Flash crashes reveal systemic fragility: Events like the 2010 Flash Crash demonstrated that market-maker withdrawal or sudden algorithm failures can destabilize entire markets within seconds.
  • Tick size reductions amplified conflicts: When minimum price increments shrunk from fractions to decimals, profits from market making compressed, pushing firms toward more aggressive strategies.
  • Preferential information access creates asymmetries: Market makers often have insights into order flow and market depth that retail investors lack, despite regulatory improvements.
  • Technology arms races raise barriers: The pursuit of faster execution creates systemic risks and advantages that smaller market makers cannot match, concentrating power.

Conflict of Interest Flow in Market Making​

The Structure of Conflicts of Interest in Market Making​

The fundamental controversy surrounding market makers stems from an irreconcilable tension: they are compensated to provide liquidity, yet profit when prices move against retail traders. A market maker who buys a stock at $50.00 and sells it at $50.05 makes money when the mid-market price stays stable. But if volatility increases or the stock's true value becomes uncertain, the market maker faces losses. This creates an incentive structure where market makers want conditions of low uncertainty and stable order flow—not necessarily conditions that serve all market participants equally.

Consider how a market maker evaluates risk. When a retail broker sends an order to sell 1,000 shares of a stock, the market maker must decide: should I buy these shares at $49.95 or $49.98? The wider the spread the market maker quotes, the more profit on each trade, but fewer orders may execute. This tension forces market makers into constant optimization. However, when a large institutional order hits the market, the dynamics shift. Institutional traders often have alternative execution venues and the bargaining power to demand better pricing. Retail traders typically cannot negotiate—they accept the market maker's quoted spread or miss the trade entirely.

This asymmetry has generated decades of regulatory concern. The Securities and Exchange Commission (SEC) has repeatedly investigated whether market makers systematically exploit information advantages. A market maker with data on aggregate order flow—perhaps seeing 100,000 shares of buy orders queued across multiple brokers—can infer that prices are likely to rise. They might widen their spread preemptively, knowing that sellers are about to be less attractive. Retail investors, lacking this view, are disadvantaged.

Payment for Order Flow: The Central Controversy​

One of the most contentious practices in modern market making is payment for order flow (PFOF). Here's how it works: brokers like Robinhood, Fidelity, or E*TRADE don't charge commission on trades. Instead, they sell information about their retail customer orders to market makers. Citadel Securities, Virtu, and other major market makers pay for this order flow—often millions of dollars annually.

The controversy hinges on a fundamental question: if a market maker is paying for your order, are they making money from you or for you? Proponents argue that PFOF actually benefits retail investors because brokers can offer commission-free trading. Without PFOF revenue, they argue, brokers would need to charge fees or restrict access. The SEC itself initially permitted PFOF under the theory that competition among market makers would drive spreads tighter to capture order flow.

However, critics argue that PFOF creates perverse incentives. When a market maker pays a broker $0.001 per share for order flow, they will still profit if they execute at a price $0.002 worse than the national best bid-offer. A retail investor selling 100 shares might receive $49.98 per share when the market is quoting $50.00 / $50.05. The market maker profits on the spread, the broker profits from the payment, and the investor is worse off. Over millions of retail trades annually, this adds up to billions in cumulative disadvantage.

In 2021, the controversy intensified when Citadel Securities revealed it was paying brokers an average of $0.001 per share for order flow, yet the SEC found that retail orders executed 1-2 basis points (0.01-0.02%) worse on average when routed to market makers versus intermarket alternatives. Subsequent studies by academic economists suggested the total welfare loss to retail investors from PFOF exceeds $5 billion annually in the US equities market alone.

Regulatory response has been divided. The SEC has issued no blanket ban on PFOF, though it has increased disclosure requirements and launched investigations into whether certain market makers are gaming order-flow arrangements. Congress has held multiple hearings, and reform proposals range from complete prohibition to mandatory execution price transparency for all PFOF deals.

The 2010 Flash Crash and Market Stability Concerns​

On May 6, 2010, the Dow Jones Industrial Average fell nearly 1,000 points in minutes—and then recovered most of those losses just as rapidly. This episode, known as the Flash Crash, became the defining moment for market-maker controversy in the digital age. The crash revealed that modern market structure, dependent on high-speed market making and algorithmic trading, could unravel catastrophically.

The proximate cause was complex: a large mutual fund initiated a $4.1 billion sale of stock index futures that overwhelmed available liquidity. As prices fell, algorithmic traders—many of them market makers—withdrew their bids to avoid losses. This withdrawal triggered a cascade: as bids disappeared, prices fell faster, triggering more algorithmic withdrawal. Within seconds, stocks like Accenture traded below $1 (having been trading above $40), and many large-cap stocks saw zero bids at any price.

The controversy here centers on market-maker withdrawal behavior. When markets become volatile, market makers have the right to stop quoting prices. This is considered essential for their protection—without this right, market makers would be forced to absorb unlimited losses during market panics. However, when all market makers withdraw simultaneously, the market becomes illiquid and prices become impossible to discover. Retail and institutional investors couldn't trade, and those forced to execute faced prices far from fundamental value.

Subsequent investigations by the SEC and Commodity Futures Trading Commission (CFTC) revealed that market makers' protective stop-loss mechanisms had fired, causing a coordinated exit. The question became: should market makers have obligations to maintain minimum liquidity during stress events? Or would such obligations be too onerous and force firms into insolvency? The regulatory response was mixed. New "circuit breaker" rules were implemented to halt trading if the S&P 500 fell too far in a short period, giving market makers time to rebalance. But no hard obligation to maintain liquidity was imposed, preserving market makers' right to exit.

For investors, the Flash Crash raised a critical concern: the market's apparent solidity masks fragility. Market makers profit during normal times and withdraw during crises. This means the liquidity you see when you check your brokerage app might evaporate if volatility spikes—particularly for less liquid securities.

Tick Size, Profitability, and Aggressive Strategies​

Until 2001, stock prices could only move in fractions (1/16 or 1/8 of a dollar). A market maker buying at $50 and selling at $50 1/8 secured a minimum profit of $0.125 per share. With that cushion, market makers could afford to be patient and operate with relatively low risk. Then decimalization arrived: prices could now move in $0.01 increments.

The decimalization controversy is subtle but profound. Overnight, the minimum spread fell from $0.125 to potentially $0.01—a ten-fold reduction in guaranteed profit. Market makers' revenue compressed dramatically. To maintain profitability, many firms responded not by accepting lower margins but by increasing volume, taking on more risk, and deploying more aggressive algorithms. This shift had multiple consequences:

  1. Higher turnover and flash orders: Market makers began using aggressive order types (like "flash" orders that showed inventory to selected traders before the public) to offset margin compression.

  2. Volatility increased: Some research suggests that lower tick sizes, while good for reducing spreads, increased intraday volatility because market makers were less able to absorb shocks passively.

  3. Concentration increased: Only firms with sophisticated technology could compete on razor-thin spreads at high volume. Smaller market makers were squeezed out, and concentration in the industry accelerated.

  4. Behavioral changes: To maintain returns, market makers began using data-mining techniques to identify trading patterns in order flow, a practice sometimes criticized as front-running or market manipulation.

The tick-size debate remains open. The SEC conducted experiments with larger tick sizes for certain small-cap stocks, and some of those experiments suggested that larger tick sizes increased spreads modestly while reducing volatility and increasing depth. However, market makers have argued that returning to larger tick sizes would raise the cost of capital for borrowing and trading.

Information Asymmetry and "Selective Disclosure"​

Market makers access information that the public doesn't have—at least not immediately. Information asymmetry between market makers and retail investors is perhaps the least discussed but most profound controversy in the industry.

When a large institutional client considers a block trade (a sale of 100,000+ shares), they typically contact market makers or brokers for a "market color"—an informal assessment of how easy it would be to execute such a trade without moving the market. During this conversation, the market maker learns valuable information: a major holder is considering selling. They now know that supply will likely increase. A rational response is to lower their bids preemptively or widen spreads.

Retail investors, meanwhile, might see prices start to drift down and assume it's due to news or sentiment shifts. In reality, it's due to informed participants' efforts to front-run the forthcoming supply. The SEC has improved disclosure requirements through rules like Regulation FD (Fair Disclosure), which prevent selective disclosure of material information. However, non-material information—like anticipated order flow—remains entirely fair game.

This information advantage compounds. Firms like Citadel Securities and Virtu employ thousands of data scientists and engineers to build models that infer future price movements from order flow patterns, tick data, and other signals available to market makers but not to the general public. While none of this is illegal, it creates a systematic advantage structure where market makers profit from information asymmetries.

Manipulation Concerns and Layering​

Regulators have periodically investigated market makers for manipulation—specifically, using orders they have no intent to fill to create false impressions of supply and demand. One tactic is called "layering": a trader places multiple large orders at progressively worse prices (widening the spread artificially), creating the impression of significant supply/demand. Once other traders respond and prices move, the original orders are canceled without executing.

The Dodd-Frank Act and later SEC rules made layering illegal. However, the challenge for regulators is distinguishing layering from legitimate order management. A market maker might place orders, see them fill partially, realize market conditions have changed, and cancel the rest. Is that manipulation or prudent risk management? The subjective nature of intent makes enforcement difficult.

A few high-profile cases have resulted in fines. In 2020, the SEC fined Virtu for $7.5 million related to failing to report certain large short sales, not precisely layering but related to transparency issues. Cases like these keep the controversy alive: market makers have sophisticated tools and information advantages that could theoretically be misused, and regulators are constantly trying to stay ahead of evolving tactics.

Technology Concentration and Systemic Risk​

As market making has evolved, technology has become the decisive factor in profitability. Firms like Citadel Securities and Virtu invest hundreds of millions of dollars annually in infrastructure: ultra-low-latency networks, data centers co-located at exchanges, machine learning models, and dedicated trading systems. The barrier to entry for new market makers has become extraordinarily high.

This concentration creates systemic risks. If one of the two or three largest market makers experiences a technology failure, the impact ripples across entire markets. In August 2013, Knight Capital—once a major market maker—deployed faulty code that caused it to lose $440 million in approximately 45 minutes. The incident revealed how quickly technology failures can destabilize markets and wiped out a major firm.

More recently, concerns about systemic risk have focused on how interconnected market makers have become with retail brokers, dark pools, and alternative trading venues. A market maker's technology failure doesn't just affect their own operations; it can cascade through the ecosystem of brokers and venues that depend on them for pricing and liquidity.

The Retail Trading Boom and Renewed Scrutiny​

The pandemic-era boom in retail trading brought market makers back into regulatory focus. As retail investor participation surged through commission-free brokers, the volume of orders flowing to market makers exploded. In 2020, market makers handled approximately 35% of individual stock trades; by 2021, that figure had climbed toward 50% in some stocks.

The intensity of scrutiny increased further during the GameStop and meme-stock episodes of early 2021. As retail traders coordinated purchases and prices skyrocketed, questions emerged about whether market makers were pressuring brokers to halt trading or restrict certain orders. While subsequent investigations found no direct coordination, the episode revealed how dependent retail brokers had become on market-maker relationships and how little transparency existed around execution practices.

The SEC and FINRA have responded by demanding additional reporting on order execution quality and PFOF arrangements. A 2021 SEC rule required brokers to disclose the amounts and average prices paid for order flow, making pricing opacity more difficult to hide. However, critics argue that mandated disclosure is still insufficient—retail investors might see that $0.001 per share was paid but have no way to judge whether this represents fair value.

Real-World Examples of Controversy Impact​

The 2010 Flash Crash caused documented losses to retail and institutional investors who were forced to execute at extreme prices. Some investors filed lawsuits, though most were ultimately dismissed because regulators had determined prices would be "busted" (trades canceled and repriced near fair value after the fact). However, this solution worked only because exchanges had authority to invalidate trades; it didn't prevent the psychological shock and losses to those unable to exit during the chaos.

The GameStop episode revealed how market-maker relationships could implicitly influence retail brokers' decisions. When brokers restricted buying in GameStop in January 2021, it wasn't because an exchange demanded it, but because brokers' financial backers—market makers and other financial institutions—were concerned about the volatility and losses. Whether this was appropriate prudence or market manipulation remains debated.

PFOF's impact on retail investors is visible in academic research. Studies comparing execution prices for identical orders routed to different venues show that orders routed to market makers via PFOF arrangements consistently executed 1-3 cents worse per share than the national best bid-offer. For a retail investor trading 100 shares, this amounts to $1-3 per trade—seemingly trivial, but aggregating across millions of retail trades annually yields tens of billions in cumulative disadvantage.

Common Mistakes​

Assuming your broker has no incentive to route your order poorly: Many retail investors believe brokers are neutral intermediaries. In reality, brokers are explicitly paid by market makers for order flow and have financial incentives to maintain those relationships.

Believing that quoted spreads are guarantees: The spread you see on your brokerage app is what the market maker is willing to quote, but during volatile periods or for less-liquid stocks, spreads widen or disappear entirely. Market makers' "best" offer is conditional on market conditions.

Not understanding that price discovery is contingent: The prices you see aren't carved in stone; they reflect market makers' current valuations and risk tolerances. During stress, those bids and asks vanish, and the notion that your $100 stock has a $100 bid/ask becomes abstract.

Conflating market maker necessity with market maker fairness: While market makers are essential for liquidity, their existence doesn't automatically mean they're treating all participants fairly. They profit from information advantages and pricing power, which are legitimate business activities but create systematic disadvantages for uninformed traders.

FAQ​

What is payment for order flow, and why is it controversial?

Payment for order flow (PFOF) is when brokers sell information about customer orders to market makers. The controversy centers on whether retail investors benefit from commission-free trading or lose more through worse execution prices than they would with a commission-based model.

Did market makers cause the 2010 Flash Crash?

The Flash Crash resulted from a convergence of factors: a large automated sell order, algorithm-driven market maker withdrawals, and interconnected trading systems that lacked circuit breakers. Market makers didn't cause it, but their withdrawal behavior amplified it.

How do market makers manipulate prices?

Common tactics under investigation include layering (placing and canceling orders to create false supply/demand impressions), spoofing (similar to layering but with intent to profit after order cancellation), and using non-public order flow information to front-run anticipated trades. Regulators have made these illegal but enforcement is challenging.

Are market makers required to maintain liquidity during crashes?

No. Market makers have the right to stop quoting prices during high volatility. However, this right is conditional: if they withdraw entirely during crises, they contribute to market instability. Regulations now include circuit breakers to prevent this, but no hard obligation is imposed on individual firms.

Can retail investors avoid PFOF?

Some brokers offer options: Fidelity, for example, allows customers to direct orders to specific venues or refuse PFOF and pay commissions instead. However, most retail brokers default to PFOF because it enables zero-commission trading, which attracts price-conscious customers.

Why do market makers care about tick size?

Tick size determines the minimum spread a market maker can earn. Larger tick sizes (e.g., 1/8) guarantee wider minimum spreads; smaller tick sizes (e.g., 1 cent) force market makers to compete on narrower margins. Decimalization compressed margins, pushing market makers toward higher-volume, more aggressive strategies.

Are market makers regulated?

Yes, through SEC rules, FINRA regulations, and exchange rules. However, oversight focuses on transparency and extreme abuses rather than preventing the inherent conflicts of interest that arise from market makers' business model.

Summary​

Market-maker controversies revolve around fundamental conflicts of interest: they profit from spreads, from information advantages, and from bid-ask asymmetries that systematically disadvantage uninformed traders. The practice of payment for order flow, while enabling commission-free retail trading, creates incentives that may not align with best execution. The 2010 Flash Crash demonstrated how market makers' conditional liquidity provision creates systemic fragility. Decimalization compressed margins, pushing firms toward higher volumes and more aggressive strategies. Information asymmetries persist despite regulatory improvements. Technology concentration among a handful of firms raises systemic risks. And the boom in retail trading has intensified scrutiny of whether market makers are treating retail and institutional clients fairly.

Understanding these controversies is essential for any investor who wants to grasp how modern markets actually function. The liquidity that enables you to trade is real, but the structure through which it's delivered is shaped by profit motives and information asymmetries that you should understand. Regulatory bodies continue to refine rules to limit abuse, but the fundamental tension between market makers' role as liquidity providers and their role as profit-maximizing firms is unlikely to disappear entirely.

Next​

Market-Maker Regulation Overview