A contagion matrix in the monitoring queue picked up a debanking event on one counterparty and pre-flagged three neighbours in the client's book before any of them had public consequences. A single risk almost never travels alone; mapping which risks pull which neighbours along changes what the standing report is watching in the days after a first event.
We keep a matrix of which risks pull which. When the primary signal fires, the matrix tells the analyst which secondary signals to look at next, on which people, on what timeline. The matrix is calibrated from prior cases; it is not a theory.
The point is not to widen the alert set. It is to narrow the follow-up. When a client asks what else we should be looking at now, the matrix gives an answer that is specific and well-supported, rather than the whole map of monitoring.
Contagion works both ways; some risks predict quieter neighbours, because a resolved case removes pressure from adjacent ones. The matrix carries both directions; half of monitoring is knowing where to stop looking.
The practical read is that risk to a private client rarely arrives as one event. It arrives as a small cluster. A frozen account is followed within weeks by a supplier who quietly stops accepting new instructions, a filing that reopens under a different heading, a piece of press that resurfaces from an archive. None of those, on its own, would prompt action. Read together, they change the plan for the quarter.
A useful contagion map does two things at once. It tells you which of the neighbouring risks are worth monitoring after a first signal, and it tells you which ones can be safely ignored so attention does not get spread thin. The second half of that is the harder discipline, and the one that separates a standing view from a noisy one.