Should On-Chain DEX Traders Worry About Front-Running?

Original Author: sysls

Original Compilation: AididiaoJP, Foresight News

Introduction

I've been thinking a lot lately about executing large-scale portfolios on decentralized exchanges like Hyperliquid.

In theory, if:

• You can achieve excess returns (alpha).
• Your positions and orders are publicly transparent, as they are on a DEX like Hyperliquid.

Then:

• You should expect a class of traders to try to front-run you, capturing your alpha.
• They would do this by executing the positions you want before you do.

The end result is that you incur higher execution costs (slippage) due to being front-run.

Imagine you want to buy $1 million worth of Bitcoin at $100,000. Coincidentally, someone has a $1 million Bitcoin sell order at $100,000. A front-runner sees your intent, steps in ahead of you, takes that sell order, and then sells that $1 million worth of Bitcoin to you at $100,100. That extra $100 is slippage that could have been avoided if your intent were hidden.

The Two Extremes of Front-Running

In theory, if you push this scenario to its "logical conclusion," almost any form of "serious trading" would be inhibited on a DEX.

However, we know this isn't the case. Many highly professional players are engaged in professional trading on Hyperliquid with alpha. So clearly, the conclusion that "players with alpha shouldn't trade on DEXes" isn't so absolute.

Can we derive an intuitive boundary for the extent of front-running from first principles, combined with existing evidence?

Clearly, if you are small and trading on a highly opaque venue like Binance, your chance of being front-run is almost zero. Being small means your trading footprint (volume) is negligible relative to the market, making you almost invisible; and even if your behavior is entirely predictable, no one can attribute your specific trading activity (orders and fills) to you personally.

On the other hand, on Hyperliquid, the most typical example of a large, highly transparent wallet is the HLP vault itself—the public market-making vault that provides liquidity to other traders on Hyperliquid. I'm fairly certain there are strategies specifically front-running HLP, and this constant pressure has effectively compressed its market-making alpha to near zero.

HLP represents a rather extreme case. First, it possesses both "extremely large size" and "extremely high transparency." It's "extremely large" because its trading footprint in illiquid long-tail assets is huge (e.g., its trade size constitutes a large proportion of the average daily volume).

Furthermore, it's "extremely transparent" because it is primarily a market maker with the explicit goal of trying to unwind existing inventory at a premium by providing liquidity. This means whenever a "large" position appears on HLP, you know it will eventually need to unwind it. Worse, you can see every single position and every single order of HLP. This allows you to adjust your own portfolio to sell to HLP more cheaply whenever you see it needs to buy to close a short position, and vice versa.

All these characteristics make HLP a particularly attractive target for front-running, not unlike how ETFs are front-run due to their mandatory, strict index rebalancing. In the hedge fund world, if you actually used the term "front-running," compliance would flag you in every dimension; the industry jargon is that index rebalancing teams are very good at providing a "service" for these ETFs by anticipating liquidity needs and earning a premium from it.

How Does Front-Running Happen?

In the classic sense of front-running, one market participant knows in advance what another market participant is going to do and then takes a series of actions to profit from that information.

Take an (illegal) example: If I am an insurance agent and I know my very wealthy client intends to buy $1 billion worth of an illiquid stock throughout today's trading session, then, at the market open, I place a $1 million market buy order, and at the close, I place a market sell order for the same number of shares.

By knowing my client's intent and actions, I manage to execute before him, letting his buying push the price up, and then I profit from the difference. This is highly illegal because I:

• Acted on insider information,
• Violated my fiduciary duty,
• Benefited at the expense of my client.

However, it's a good example because it clearly shows that I can profit simply by knowing another market participant's intent and actions and being able to estimate the outcome of those actions to position myself advantageously.

Every day, front-running happens on a smaller scale and with lower illegality. Trading algorithms don't need to be told to approximate intent; they use publicly available information (orders, fills, positions) that everyone can access. Then, they estimate the market outcome of this approximated intent and decide whether to act based on the expected value of "front-running."

From this, we can infer that the transparency and leakage of your "intent" are the primary determinants of how easily you can be front-run.

The Gradient of Front-Running

Okay, so now we know that if you are small and on an opaque venue, you don't need to worry about front-running because no one can discern your intent. Similarly, if you are large, on a transparent venue, and your intent is very transparent (like HLP), you are destined to be front-run to oblivion.

But these extremes aren't very helpful for the vast majority of traders. We care more about the "middle ground." As mentioned above, what ultimately determines your susceptibility to front-running is how transparent your intent is.

Even if you are large and trading on an opaque exchange, it's not easy for others to front-run you. Your orders will appear as a "large footprint" as part of the daily volume, but attributing all orders to a "single entity" isn't straightforward unless your trading style is extremely transparent—for example, you have no randomization, you trade with fixed lot sizes or fixed notional split orders, or you send split orders in a very deterministic pattern (e.g., every 30 seconds).

If you can hide your intent—for instance, by randomizing your trade size, randomizing the timing and intervals of sending split orders, and avoiding placing buy orders that are too large relative to the average daily volume or the order book depth—then it becomes difficult for others to attribute your orders to one person. The market might sense significant buying interest in general but may not be able to attribute that buying interest to an informed party with alpha, and thus won't price liquidity accordingly.

Thankfully, we can actually extend this to transparent exchanges. Although there are many vaults on Hyperliquid and Lighter, and their operations are relatively transparent, actually front-running these vaults' trades is not simple.

The conclusion is: Unless you are quite large (e.g., an institutional vault managing hundreds of millions of dollars), you have almost nothing to worry about regarding front-running.

The Limitations of Front-Running

Trying to extract alpha from front-running without breaking the law is itself a practice of an alpha strategy. You are modeling intent based on public information (orders, fills, positions), which inherently carries model risk.

Orders, fills, and positions may be visible, but intent is not. A limit order sitting there could represent alpha, inventory management, or hedging. Models that assume every order is backed by alpha will be slowly eroded by countless misjudgments.

Furthermore, even assuming you can extract intent relatively accurately. Even then, alpha itself is not "all-powerful." All alpha comes with a certain amount of statistical noise, and your portfolio is not only exposed to the statistical noise of the alpha but also bears the additional model risk from misinterpreting certain behaviors as alpha.

You might say, if I blindly copy the target's actions 1:1, I would certainly capture all the alpha—but the problem is, this actually exposes you to the risk of being exploited. If you send the same buy order every time the target acts, then when the target wants to sell, it can first place a limit buy order, watch you place the same buy order, immediately cancel its order, and then sell to you instead. So you see, thoughtless front-running itself creates vulnerabilities.

It should also be remembered and recognized that alpha has a time horizon. Some alpha is fleeting, and attackers themselves may not be able to exploit it (e.g., high-frequency taker alpha); other alpha lasts very long, and attackers may give up because they are unwilling to bear the risk with you for that long (e.g., rebalancing trades over days or weeks).

Finally, even if you have an extremely sophisticated front-runner behind you, in practice, its impact would only manifest as a few basis points. If you truly have persistent alpha, many strategies can easily absorb those few extra basis points of cost.

How Not to Be an Easy Target

Even knowing it's not that simple, as a smart, alpha-generating market participant, your task is still to hide your intent, making it as difficult as possible for attackers to front-run you.

You can do many things, varying in complexity and effectiveness. The first thing you should do is obsessively collect telemetry data and logs so you can quantify the specific "extent" to which you are being front-run (if it exists at all). You can do this by analyzing the mark price, slippage, and impact cost of a large sample of your orders and fills.

Then, once you have the data, you can adopt a series of defensive measures. A common thread among these measures is: You should make it less obvious "whether you want to buy or sell," "how much you actually want to buy or sell," "how urgently you want to buy or sell," and "whether you are trading an alpha position or a hedging position."

Some simple methods to obfuscate your intent are: placing two-sided quotes simultaneously, using random sizes, and operating at intervals that are not always deterministic.

A (high-level, complex) method that can effectively obfuscate your positions is: splitting your portfolio into multiple wallets, each internally maintaining a roughly neutral long/short balance with good "margin efficiency" on its own. Within each wallet, you hold both alpha-generating positions and hedging positions. Some wallets are 80% alpha positions plus 20% hedging positions; others are 80% hedging positions plus 20% alpha positions. Over time, you rotate the "type" of each wallet and randomly introduce new wallets and retire old ones.

This means if an attacker only tracks one of these wallets, they might end up tracking a wallet primarily used for hedging, getting stuck in loss-making positions intended for hedging. If they track all wallets, you can further obscure your true intent through a series of contradictory operations. What exactly that would look like is left to the reader's imagination!

Finally, there are already (external) solutions on the market that address this issue. I haven't personally used them, but in principle, they solve the privacy problem through one of two methods:

Aggregating orders, matching them internally first, then executing the remainder on the DEX, and finally attributing the positions back to you—this is no different from how a hedge fund's central liquidity book aggregates orders from various strategy pods and then allocates positions back.

Splitting your orders across multiple wallets along with orders from other users of the solution, executing on the DEX, and then attributing the positions back to you.

Conclusion

If you are a retail trader with a small trading size, you probably have little to worry about, even when trading on transparent DEXes. Front-running has its own limitations that make it difficult for others to truly profit at your expense.

That said, as your trading size gradually increases and the quality of your alpha improves, this naturally incentivizes front-runners to target you. At that point, you should invest more resources in obfuscating your intent to make their lives as difficult as possible.

This issue is by no means "solved," and for any institution or trader executing large-scale trades in open, decentralized, transparent liquidity venues, this will be an ongoing "cat-and-mouse game."