How ECNs Assess Toxicity in FX Order Flow
Summary
The document explains how electronic communication networks may assess whether a liquidity taker’s FX flow is difficult for liquidity providers to monetize. Its central diagnostic is an aftermath chart: average mark-to-market profit from the provider’s perspective, plotted against elapsed time or subsequent top-of-book updates, sometimes by currency pair. At trade inception, this measure is typically around half the bid-ask spread.
The speed at which the curve approaches zero indicates how long a provider has, on average, to earn the spread after trading with that participant. A rapid decay suggests the flow is sharp and may be labeled toxic because the provider has little time to offset or monetize the position. Another answer associates toxicity with aggressive orders and short-term predictive alpha. The discussion is brief and relies on cited answers rather than presenting data or a validated classification method; its second observation comes from equities and is offered as potentially relevant to FX.
Key ideas
- ECNs can use aftermath charts to assess the post-trade economics of a liquidity taker’s flow.
- The chart tracks a liquidity provider’s average mark-to-market result over time or book updates.
- A short time for the aftermath curve to reach zero indicates limited opportunity to monetize the spread.
- Aggressive execution combined with short-term alpha is also described as a source of sharp flow.
- The discussion offers conceptual indicators, not a tested method for avoiding toxicity labels.
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Full text
# What is Toxic FX Flow debate? # What is Toxic FX Flow debate? So, basically I want to debate and find out the real reason behind being flag by ECNs and venues as "toxic". How to avoid being flagged? What kind of strategies are toxic and why? Below is an article found by a brokerage firm... so the opinion in that article couldn't be that objective. Article about toxix FX flow Any thoughts? ## Answer by mpeac (score 5) https://quant.stackexchange.com/a/29761 The primary way ECNs determine if a liquidity taker's flow is 'toxic' or not is by looking at aftermath charts. The aftermath chart shows the average mark-to-market profit of trades done by the liquidity taker as a function of either time or number of top-of-book updates (optionally broken down by currency pair). The trade profit is usually viewed from the liquidity provider's perspective, and so the aftermath chart is typically equal to half the average bid/ask spread at the inception of the trade, corresponding to the y-intercept of the aftermath chart. Now, the time it takes for the aftermath curve to decay to zero represents the average amount of time a liquidity provider has to monetize the spread earned at inception after trading with the given liquidity taker (by matching the trade with another liquidity taker, for example). If this amount of time is relatively short (typ. a few seconds), then the flow is harder to monetize. Such flow is considered 'sharp', and very sharp flow is considered 'toxic'. ## Answer by LazyCat (score 1) https://quant.stackexchange.com/a/26197 Usually it's aggressiveness of your orders + short term alpha. While it's equities not FX, I think you may find something interesting in the recent Barclays LX darkpool lawsuit documents.
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This summary was written by Stratmill's research agent from the original; it is not a copy of the source.