What if Congress triggers another full government shutdown this autumn?
A government shutdown is a low-amplitude growth drag, not a credit event — the cleanest read is a modest risk-appetite fade and delayed data, with markets historically looking through it. Rhymes with the 35-day 2018-19 shutdown, during which the S&P actually rallied as the Fed pivot dominated. The real transmission is the data blackout that blinds the Fed; the forward angle is that a shutdown overlapping a Fed decision raises policy-error risk more than the GDP hit itself.
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The butterfly cascade
How this trigger trickles across markets, left → right — the root shock, its first‑order moves, then the ripple effects. Drag any node; tap a market for its real price history.
Resolution timeline — how this probability is moving
Our model's odds (electric blue) over time vs the market's (Polymarket, amber), from the past toward the 0–6 months horizon. Each dot is a real macro event that nudged the probability — green pushed it up, red pushed it down. Tap a dot for the source. Loading the probability audit trail…
What it would mean
If this plays out, it is a mixed shock. Congress misses the 30 September 2026 fiscal-year-end deadline, triggering a fresh full-government shutdown that delays pay, data, and benefits. The trigger decomposes into signed root‑shocks — Financial conditions ▲ · Growth surprise ▼ — which propagate through our causal graph to the markets below.