Two accounts, linked by a single strong trading relationship, executed thirteen direct fills against each other plus two round trips inside a fourteen-second burst. Fifteen self-trading events in total, worth ninety-five pence, in a market whose entire observed volume was about forty-three dollars.
It would be easy to dismiss. We keep it for two reasons. The first is that it was the detector's first live confirmation: the rule was written to catch exactly this shape, and it did, on activity nobody had pointed it at.
The second is that the signature is scale-invariant. The identical pattern with ten thousand dollar fills is a serious money-laundering event.
Signature
What the matcher looks for, at any size.
- Cluster size
- Exactly 2 accounts
- Relationship
- A single strong counterparty edge, no wider web
- Burst density
- 10 or more direct fills between the pair inside 60 seconds
- Pattern
- Alternating buy and sell of the same outcome
- Net position
- Near zero
- Market depth
- Thin: total in-window volume under $50 in this instance
Recording small cases with the same care as large ones is what makes a pattern library useful rather than a highlights reel. The size of a finding tells you how urgent it is. The shape of it tells you what it is.