Part of the The Bayesian Investor — A Primer for the CIO series.

Use Case 3 — "When One Domino Falls": Cross-Asset Stress Testing With Private-Asset Look-Through

What it does. This answers the single most important question for an investment committee: if one asset is hit by a shock, what happens to everything else — including the private positions we can't directly observe or mark daily? It traces the direct transmission of stress across public markets and then "looks through" private-equity and real-estate funds to their public exposures, so the committee can see how an unlisted holding would react to a market event.

The method. (Bayesian graphical model with bootstrap posterior edge inclusion for the stress map; public-comp look-through for private positions; stale-mark detection via graph-shift monitoring.)

The analogy — the domino table. Set up a row of dominoes. Tapping one domino doesn't knock down the whole table at random — it knocks down the ones actually touching it, which then knock down the ones touching them. The path of the fall follows the real connections, not the surface similarities. If two dominoes happen to be painted the same color, they don't move together unless they're physically linked. This tool maps the real physical links, then lets you tap any domino and watch the true path of the fall.

The analogy — the X-ray. A private fund's value isn't published daily; it's a mark that gets updated periodically. But the fund holds investments that respond to public markets. The X-ray sees through the fund's wrapper to its underlying public exposures, so a market shock can be translated into "what this private position is probably doing right now" — even before the next formal mark arrives.

The analogy — the freshness label. When the public mirror of a private position starts drifting away from the last private valuation, the tool flags it: "this private mark may be stale — the world has moved, but the number hasn't." That's a quiet, valuable warning that the committee's picture of the private book is out of date.

Why it matters for investing. For an institution with private assets, the hardest reporting problem is: "if markets fall 10%, what's our total book doing, including the stuff we can't mark daily?" This tool gives the committee a defensible, transparent answer — and flags when private valuations need refreshing.

Why it beats the traditional approach. Correlation-based stress testing confuses "in the same room" with "directly connected," so it mis-attributes which shocks actually travel where. This tool traces direct links, attaches confidence to every claim, looks through private wrappers to their real exposures, and alerts when private marks go stale — none of which the traditional single-number stress test can do.