What if the US imposes flat per-parcel import duties?
Flat per-parcel duties plus inspection are a de minimis aftershock aimed at Shein/Temu direct-ship, so the clearest move is e-commerce import-cost inflation and a customs backlog, not a broad semis hit. Rhymes with the 2025 de minimis removal that already collapsed parcel volumes from China. China is the dominant low-value parcel origin; the forward angle is this is a margin/logistics squeeze on discretionary retail, so the cascade over-weights TSMC/Nvidia which have no parcel exposure.
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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. With de minimis gone, US imposes flat per-parcel duties and tighter inspection, deepening the parcel-import collapse and customs backlog. The trigger decomposes into signed root‑shocks — Inflation surprise ▲ · Trade tension ▲ · Consumer spending ▼ — which propagate through our causal graph to the markets below.