Red Sea & Bab el-Mandeb: Houthi shipping risk, odds and oil
As of 2026-10-26 04:32 UTC, Polymarket prices “Bab el-Mandeb Strait effectively closed by...? — December 31” at 16.5%; GeoShockBoard's judgment is 10%. Status: Houthi barrage on Saudi Arabia continued 25 Oct (10 ballistic missiles at the south, plus Riyadh and Khamis Mushait. After 7 similar past shocks, oil's median move over 5 sessions was +3.08%. Market context, not investment advice.
Odds: crowd vs GeoShockBoard
| Polymarket market (exact name) | Crowd "Yes" | Ours* | Gap |
|---|---|---|---|
| Bab el-Mandeb Strait effectively closed by...? — December 31 Bab el-Mandeb effectively closed by Dec 31 | 16.5% | 10% | -6.5 |
| Saudi-Houthi ceasefire agreement announced by...? — December 31 Saudi–Houthi ceasefire announced by Dec 31 | 20.5% | 15% | -5.5 |
| Perim Island no longer under Houthi control by...? — December 31 Perim Island out of Houthi control by Dec 31 | 20.5% | 20% | -0.5 |
What would change my mind: A UKMTO-confirmed hit on a non-Saudi hull, or Egypt's parliament voting no.
Killer tests (missing data = not met; tests whose date has not arrived = pending)
| JMIC threat level falls JMIC rates Bab el-Mandeb below SUBSTANTIAL | NOT MET |
| War-risk premium normalizes A wire quote puts the Saudi-linked war-risk premium near 1% of hull value | NOT MET |
| Saudi-linked tankers transit Saudi-linked tankers resume southbound Bab el-Mandeb transits | NOT MET |
| Generalization trigger (escalation) UKMTO-confirmed Houthi hit on a non-Saudi-linked merchant hull | NOT MET |
Game-theory read
A discriminating blockade. Narrow targeting of Saudi-linked ships keeps a wider coalition from forming against the Houthis, which is calibrated, selective violence (Dixit & Nalebuff, brinkmanship [inference on fit]). Egypt is not a free actor: it is the Saudi coalition's marginal member, and a 'yes' vote on 26 Oct turns its threat into a commitment (Schelling's burning bridges). The equilibrium breaks if the Houthis hit a non-Saudi hull, because carriers would then re-price the whole strait.
- Houthis: Selective blockade: hit Saudi-linked targets and leave most traffic alone, which keeps the leverage without uniting the world against them.
- Saudi Arabia: Retake the coast and nodes like Perim and Mocha to remove the leverage at its source, and recruit Egypt to share the cost.
- Egypt: Suez revenue depends on a calm strait, but entering the war means an open-ended commitment.
- Carriers: Fuel and congestion costs favor Suez; one strike on a container ship reverses that calculation.
If it escalates: history says
| Asset | +1 session | +5 sessions | +20 sessions |
|---|---|---|---|
| Oil | +1.83% ↑86% n=7 range -0.90% to +14.61% | +3.08% ↑86% n=7 range -0.04% to +9.85% | +1.11% ↑83% n=6 range -5.04% to +10.92% |
| Gold | +0.24% ↑57% n=7 range -0.32% to +1.60% | +0.95% ↑86% n=7 range -0.73% to +1.64% | +1.77% ↑67% n=6 range -1.43% to +10.41% |
| US defense (ITA) | +0.72% ↑71% n=7 range -0.99% to +1.10% | +0.84% ↑86% n=7 range -0.26% to +4.08% | +3.40% ↑67% n=6 range -4.48% to +9.75% |
| S&P 500 | +0.08% ↑57% n=7 range -0.31% to +0.74% | +0.75% ↑57% n=7 range -1.49% to +1.62% | +4.29% ↑83% n=6 range -1.23% to +5.15% |
| VIX (pts) | +0.06 ↑57% n=7 range -0.39 to +0.93 | +0.75 ↑57% n=7 range -1.58 to +3.23 | -0.38 ↑50% n=6 range -4.52 to +2.51 |
What changed this week
- Coalition (25 Oct): intercepted 10 Houthi ballistic missiles toward southern Saudi Arabia, plus a ballistic missile and drone toward Riyadh and a cruise missile toward Khamis Mushait; Civil Defence says debris injured 2 and damaged 3 homes and 7 vehicles. source T1
- King Khalid International Airport in Riyadh resumed operations on 25 Oct (T1 domestic, T2 international) after the 10 Oct strike; Houthi spokesman Saree says it remains a 'military target'. source T2
- Houthis claim seven operations including Aramco facilities in Yanbu; the US issued travel warnings for Saudi Arabia and 11 other regional countries. source T2
- Coalition (24 Oct): intercepted Houthi ballistic missiles toward Riyadh, Taif and Yanbu and a drone over the Eastern Province; brief alerts in Mecca, Jeddah, Taif and Yanbu. source T2
- Saudi Civil Defense: interception debris fell in Wadi Al-Mughammas (about 20 km from Mecca's Grand Mosque), Jeddah's Al-Nuzha, Taif and Rabigh; no casualties reported. source T1
- Coalition intercepted a Houthi ballistic missile toward Riyadh and another toward Khamis Mushait on 23 Oct; coalition count for October: at least 14 ballistic missiles and 60+ drones, 24 killed and 374 injured in the kingdom. source T2
Change log
- 2026-10-22: Crowd odds only (v2) → First GeoShockBoard weights and killer tests published. v3 schema: own weights, falsifiable killers, change log
- 2026-10-23: Saudi–Houthi ceasefire by Dec 31: 20 → 15. Houthi campaign widened to Dammam, Riyadh, Yanbu and Abha; US ordered staff out of Saudi Arabia.
FAQ
What are the Polymarket odds for “Bab el-Mandeb effectively closed by Dec 31”?
As of 2026-10-26 04:32 UTC, the Polymarket market “Bab el-Mandeb Strait effectively closed by...? — December 31” priced Yes at 16.5%. Prices are trade-implied probabilities and change continuously.
What is GeoShockBoard's own call?
Bab el-Mandeb effectively closed by Dec 31: 10%; Saudi–Houthi ceasefire announced by Dec 31: 15%; Perim Island out of Houthi control by Dec 31: 20%. These are GeoShockBoard judgments, logged on the track record and scored at resolution.
What would change the outlook?
A UKMTO-confirmed hit on a non-Saudi hull, or Egypt's parliament voting no.
Which tests are being watched?
JMIC threat level falls: not met. War-risk premium normalizes: not met. Saudi-linked tankers transit: not met. Generalization trigger (escalation): not met. Missing data counts as not met; tests whose date has not arrived are pending.
How did oil move after similar past shocks?
Across 7 past shipping/energy hit events since 1990, oil's median move over 5 sessions was +3.08% (range -0.04% to +9.85%); it rose in 86% of cases. Past reactions do not predict future ones.
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