Brokerage risk
What is toxic flow? How brokers identify it
Toxic flow is client order flow that is consistently profitable against a broker's own book. The word describes its effect on the broker's B-book, not the client: most toxic flow is legal, and many brokers welcome it as long as it is routed to the right place.
By Admin · · 3 min read
Why it matters
On the B-book, the broker is the client's counterparty, so every gain on a client position is a loss for the book until it is hedged. A small group of consistently winning clients can outweigh the spread earned from everyone else. Spotting that flow early lets the broker route or hedge it instead of absorbing it.
Common types
- Informed or skilled trading: clients with a real edge, such as strong research or a disciplined strategy. Legitimate, but costly on a B-book.
- Latency arbitrage: trading on prices that are a fraction of a second out of date, when the broker's price feed lags a faster market.
- News trading: opening positions in the seconds around major economic releases, when prices move faster than quotes update.
- Very short-term scalping: strategies that profit from small, repeated price moves or from execution delays.
- Coordinated accounts: several accounts placing matching trades, sometimes to take advantage of promotions or account terms.
Signs brokers measure
| Sign | What it looks at |
|---|---|
| Holding time | Positions held for seconds rather than minutes or days |
| Win rate and consistency | A high share of profitable trades over many weeks, not a lucky run |
| Markout | How the price moves after each trade, for example 1, 5 and 60 seconds later; flow that is right straight away, again and again, is informed |
| Timing | Orders clustered around news releases or price-feed updates |
| Account links | Trades that mirror each other across accounts |
Fair responses
Brokers usually route such flow to the A-book, where liquidity providers price it, or hedge the exposure it creates. Some also review limits under the client agreement. Every response must stay within the client agreement, the broker's order execution policy and its regulator's rules on fair treatment of clients.
How technology helps
Software can score each client's flow continuously, flag accounts whose pattern changes and show the dealing desk where its routing rules no longer fit. Fellowdata's risk management technology includes client risk profiling for this work; A-book vs B-book explains the routing models themselves.
Common questions
Is toxic flow illegal?
Usually not. It means flow a B-book loses money on; the client may be trading entirely within the rules.
Should brokers refuse toxic flow?
Many route it to liquidity providers instead. Any restriction must follow the client agreement and the regulator's rules.
Can software identify it on its own?
Software flags patterns; people on the dealing desk review them and decide.
Sources
Checked on .
- Easley, López de Prado and O'Hara: Flow Toxicity and Liquidity in a High-frequency World: The Review of Financial Studies (2012). Defines order flow as toxic when it adversely selects market makers, who may not know they are providing liquidity at a loss