What if a block-size hard fork splits Bitcoin in two?
A contentious block-weight hard fork splits Bitcoin, fracturing hashpower and breaking replay protection, so exchanges scramble and holders de-risk into the uncertainty — BTC drops and high-beta ETH/alts fall more. Rhymes with the 2017 BCH fork and the 2018 BCH-SV hash war, which spiked volatility and pressured BTC into the split before resolving. Forward angle: today's ETF-and-treasury-dominated holder base is far less ideological about forks, so a messy split risks heavier institutional outflows than the 2017 retail-led episode.
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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 1–3 years 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 risk-off shock. A bitter dispute over raising Bitcoin's block-weight limit splits the chain, fracturing hashpower, exchanges, and replay-protection guarantees. The trigger decomposes into signed root‑shocks — Crypto confidence ▼ · Risk appetite ▼ — which propagate through our causal graph to the markets below.