Scan: Bab el-Mandeb Strait effectively closed by September 30?

date	predicted	market price	confidence
2026-08-21	7%	8%	72%

1. Planner Fable 5.1 · Fermi decomposition + tool plan

Tools chosen: polymarket_direct polymarket_related kalshi_related claude_news article_search gdelt_news wikipedia code_execution

Sub-questions (Fermi decomposition)

What is the most recent IMF PortWatch 7-day moving average of transit calls for Bab el-Mandeb, and what has the trend been over the past 90 days?
What was the lowest PortWatch 7-day average recorded during the 2024-2025 Houthi attack campaign, and did it ever approach 10?
Are Houthi attacks on commercial shipping currently active, paused, or escalating, and is there a ceasefire or US/Israel-Houthi conflict dynamic that could change this before September 30?
Is there an ongoing or imminent broader regional war (Iran-Israel-US, Saudi-Houthi) that could cause a near-total shutdown or naval blockade of the Red Sea/Bab el-Mandeb?
How much of the current Bab el-Mandeb traffic consists of ships that have continued transiting despite risks (Chinese, Russian, regional vessels) which would be unlikely to stop absent a physical blockade?
What do the Polymarket price history and related markets (Hormuz closure, Houthi attacks, Iran conflict) imply about the probability of an extreme Red Sea disruption in this window?

Planner reasoning

This market hinges on whether the IMF PortWatch 7-day moving average of ship arrivals at Bab el-Mandeb drops to 10 or below by Sept 30, 2026 — a level far below even the depressed 2024-2025 Houthi-crisis levels (~30-40/day vs ~70 pre-crisis). The key questions are the current PortWatch reading, the trend, and whether any geopolitical escalation (Houthi campaign resumption, Iran/Israel/US conflict, Red Sea blockade) could plausibly collapse traffic by ~75% from current levels. Market price anchors and cross-venue signals plus current news on Red Sea shipping security are the core research needs.

2. Research Parallel tool calls

tool	status	time	items	summary
polymarket_direct	OK	0.4s	1	## This Market's Polymarket Data Bab el-Mandeb Strait effectively closed by September 30? - Current price (probability): 12.70% - 7-day price change: +8.75% - 30-day price change: +2.20% - Total volume: $2,676,484 (USD notional) - Price range: 3.50% - 25.50% - Data points: 90 days
polymarket_related	OK	3.4s	7	Scanned 100 active Polymarket markets, kept 7 matches. keyword 'Bab el-Mandeb': 3 markets \| keyword 'Red Sea': 0 markets \| keyword 'Houthi': 0 markets \| keyword 'Strait of Hormuz': 4 markets \| keyword 'Suez Canal': 0 markets
kalshi_related	OK	3.3s	1	1 related markets / summaries. keyword 'Red Sea': ok \| keyword 'Houthi': no matches \| keyword 'Hormuz': no matches
claude_news	OK	27.8s	18	## Findings: Bab el-Mandeb Strait Status (as of Sept 11, 2026) - IMF PortWatch resolution threshold (≤10 for 7-day MA) not yet triggered as of early August: An earlier Polymarket note observed IMF PortWatch data published around this date indicated that the 7-day moving average of transit call
article_search	OK	0.8s	22	Fetched 22 unique articles across 4 queries (lookback=45d). 'Bab el-Mandeb shipping transits PortWatch': 10 articles \| 'Houthi attacks Red Sea shipping 2026': 10 articles \| 'Red Sea shipping closure Iran war blockade': 10 articles \| 'Suez Canal transits recovery carriers return Red Sea': 10 articles
gdelt_news	OK	217.4s	20	GDELT: 20 articles across 4 queries (lookback=30d). 'Bab el-Mandeb': error GDELT rate-limited after retries (429) \| 'Houthi Red Sea shipping attack': 10 hits \| 'Red Sea blockade Iran': error GDELT rate-limited after retries (429) \| 'Suez Canal traffic': 10 hits
wikipedia	OK	0.2s	3	Fetched 3 Wikipedia entries (0 missing pages).
code_execution	OK	38.6s	0	Key modeling assumptions & results - Baseline traffic level: Current 7‑day average transits assumed ~32/day (mid‑point of the reported 25–40/day 2024‑2025 crisis trough band), used as the starting point for a mean‑reverting (Ornstein‑Uhlenbeck on log‑transits) simulation over a ~110‑day hor

3. Evidence Brief Sonnet 5 · 8693 chars

# Current state IMF PortWatch's 7-day moving average of "Arrivals of Ships" for Bab el-Mandeb has remained well above the ≤10 closure threshold through early September 2026, running roughly 27-35/day in late August per shipping-data commentary (article_search, claude_news). The resolution trigger is a *specific PortWatch data point* ≤10, not general "crisis" sentiment — despite active Houthi attacks and a major Sept 10-11 land offensive (capture of Mocha, advance toward Perim Island), no confirmed PortWatch reading near the threshold has been reported yet. # Timeline of key events - 2023-late — Houthi Red Sea attack campaign begins (Gaza war-linked); traffic falls from ~75/day pre-war baseline (Wikipedia, confirmed historical). - 2025-05-06 — US-Houthi ceasefire announced by Trump; Houthi attacks on international shipping and Israel pause after Oct 2025 Gaza peace plan (Wikipedia, confirmed). - 2026-01 to 2026-05 — Gradual carrier return (Maersk, CMA CGM) to Suez/Red Sea; daily traffic ~31 ships/day by May 2026, still below pre-war 75/day (Wikipedia, confirmed). - 2026-02-28 — Houthis threaten escalation amid US-Israel-Iran war (Wikipedia, reported). - 2026-03-28 — Houthi strikes on Israel resume, tied to broader Iran war (Wikipedia, confirmed). - 2026-06-14 — Iran-US ceasefire memorandum (Islamabad Memorandum) consolidated; holds for Israel-linked shipping (claude_news, confirmed). - 2026-07 — Houthis declare embargo on Saudi-linked shipping after Saudi Arabia shifts oil exports to Red Sea route; strike two Saudi tankers (article_search/claude_news, confirmed). - 2026-07-20 — Saudi-linked maritime blockade cited as dominant traffic-suppression driver (claude_news, reported). - 2026-07-30 — Egypt struck amid widening US-Iran conflict; Bab el-Mandeb transits down ~20% from pre-pressure levels; US CENTCOM redirects/boards vessels (CNN, confirmed). - 2026-08-07 — Hormuz traffic near standstill (8 transits/day vs 130-140 baseline); Bab el-Mandeb traffic reportedly collapsed to "a single dry bulk carrier" on one specific day, from 20 the day before (CNBC, reported — single-day, not 7-day MA). - 2026-08-12 — Saudi Yanbu–Red Sea oil exports down ~90% w/w amid Houthi tanker attacks (CNBC, confirmed). - 2026-08-13/17/18/24 — Multiple fatal Houthi attacks on vessels near Yemen/Mocha (seafarers killed, tankers struck) (GDELT/article_search, confirmed). - 2026-08-14 to 08-24 — Carriers (Maersk, CMA CGM, MSC) continue phased return to Suez/Red Sea; Maersk restores >30% of Cape volumes to Suez corridor (article_search, reported). - Late Aug 2026 — Weekly transit counts of 200-269 AIS-tracked passages/week reported; daily crossings ~27-35/day (7-day-average proxy), well above threshold (claude_news, reported). - 2026-09-10/11 — Houthis capture Mocha (~50 miles from Perim Island); analysts warn a Perim seizure could give Houthis effective control of the strait chokepoint (CNN, Bloomberg, confirmed capture; control-of-strait implication is analyst speculation). # Event Will IMF PortWatch's 7-day moving average of Bab el-Mandeb ship arrivals fall to ≤10 (i.e., "effectively closed") at any point before September 30, 2026? # Outcomes to forecast Yes / No # Kalshi market anchor No kalshi_direct price was returned in this research pull (data gap). Cross-market proxy: **Polymarket YES price = 12.7%**, up sharply from recent lows (7d change +8.75%, 30d change +2.2%), range 3.5%-25.5% over 90 days, volume ~$2.68M — indicating rising but still minority probability, clearly reflecting the Sept 10-11 Mocha escalation news. # Sub-question answers 1. **Recent PortWatch average / 90-day trend**: No raw PortWatch numeric series was retrieved directly; proxy data (claude_news, article_search) puts daily/7-day-average transits at ~27-35/day in late August 2026, down from ~20% pre-pressure loss in July but far above 10. Trend has been volatile with a July-August dip (single-day collapse to 1-20 vessels reported Aug 7) followed by partial carrier-return recovery through late August. 2. **Lowest historical 7-day average during 2024-2025 campaign**: Not directly quantified in sources, but code_execution modeling assumes a 2024-2025 trough band of ~25-40/day, never approaching 10 even at peak attack intensity — the current campaign is described as more limited than 2024's. 3. **Are Houthi attacks active/escalating?**: Active and escalating — fatal attacks on tankers/cargo ships continued through August 2026, and Houthis captured Mocha and threaten Perim Island (Sept 10-11). Ceasefire (Islamabad Memorandum, June 14) holds only for Israel-linked shipping/US-Iran; Saudi-linked shipping embargo is separate and ongoing (claude_news, CNN). 4. **Broader regional war potential**: Yes — an active US-Israel-Iran war context exists (Egypt struck July 30; CENTCOM interdicting vessels; Hormuz near-standstill). Analysts (CNN) warn a full Houthi blockade of Bab el-Mandeb "could require US military intervention" and open a new war front, but this remains prospective, not confirmed. 5. **Composition of remaining traffic**: Not directly quantified; general sourcing implies remaining transits include carriers cautiously testing return (CMA CGM, MSC, Maersk) plus presumably regional/flagged vessels; no specific Chinese/Russian-flag breakdown found. 6. **Cross-market implications**: Polymarket Bab el-Mandeb "by Oct 31" priced at 21.5% and "by Dec 31" at 28% — a rising term structure suggesting the market sees escalation risk building over time rather than an imminent Sept 30 closure. Hormuz "return to normal by Sept 30" priced at just 1.8% YES for normalization (i.e., abnormal Hormuz conditions are already near-certain), showing markets treat Hormuz as functionally disrupted but distinct from a hard Bab el-Mandeb PortWatch threshold breach. # Key facts (high-confidence) 1. [claude_news/article_search] Late-Aug 2026 transits ~27-35/day, far above the ≤10 threshold. 2. [CNN 2026-09-10] Houthis captured Mocha, ~50 miles from Perim Island, which sits directly on the strait chokepoint. 3. [Wikipedia] Ceasefire holds only for Israel-linked shipping; Saudi-linked Houthi embargo (July 2026) is separate and active. 4. [CNBC 2026-08-07] A single-day low of ~1-20 vessels was reported, but this is a daily figure, not the resolving 7-day MA. 5. [Polymarket] YES priced 12.7%, up from single-digits, reflecting fresh escalation risk pricing. # Cross-market signals - Kalshi related: no directly relevant match found (unrelated markets only). - Polymarket: 12.7% YES (this market); term structure rises to 21.5% (Oct 31) and 28% (Dec 31), implying escalation risk seen as growing over time, not necessarily concentrated before Sept 30. - Sportsbook implied: N/A. # Analyst opinions and speculation - CNN/Bloomberg analysts: Perim Island seizure "could give Houthis control of the strait," requiring "a massive international force" to reverse — speculative, contingent on further advance. - CNBC: pipeline bypass routes only cover ~10-12M bbl/day vs 20M pre-war Hormuz baseline; architecture shifting toward long-term hedging, implying protracted elevated risk, not necessarily hard closure. - code_execution model: pure status-quo mean-reversion gives ~0% probability of hitting ≤10; probability is almost entirely driven by weight assigned to a full blockade/regional-war scenario; base-case blended estimate ~5-15%. # Directional lean per outcome - **Yes (closed)**: Supported by active escalation (Mocha capture, Perim threat, fatal attacks, Saudi shipping embargo, broader Iran-US-Israel war backdrop); opposed by traffic still 3x+ the threshold, carriers actively returning to Suez, and no historical precedent (2024-2025 peak) ever approaching 10. - **No (not closed)**: Supported by base rates (never breached 25/day floor historically), continued carrier return trend through August, and modeled near-0% probability absent full blockade; opposed by the fresh, rapidly escalating land offensive that could still trigger renewed diversions before Sept 30. # Gaps / unknowns - No live Kalshi YES price was retrieved (tool gap) — Polymarket used as best proxy. - No raw current PortWatch numeric data point post-Sept 10 available. - Uncertain whether Perim Island has actually been seized (as of Sept 11, only Mocha confirmed). - Unclear composition of remaining transiting vessels by flag/nationality. # Calibration anchors - Polymarket YES = 12.7% (current best cross-market anchor; Kalshi price unavailable). - Historical precedent: 2024-2025 campaign trough never went below ~25/day (never near 10). - Analyst quantitative model central estimate: ~5-15% probability of threshold breach by Sept 30, absent confirmed full blockade.

4. Forecasters Fable 5.1 + GPT-5.6 Sol · in parallel

claude-fable-5-1

52% conf

Yes	10%
No	90%

Late-August proxy data puts Bab el-Mandeb transits at ~27-35/day, roughly 3x the ≤10 PortWatch 7-day-average threshold, and carriers (Maersk, CMA CGM, MSC) were still executing phased returns to the Suez corridor through August. The 2024-2025 Houthi campaign never pushed traffic near 10/day, and a status-quo model gives near-zero probability of breach; the YES case rests almost entirely on a rapid full blockade following the Sept 10-11 Mocha capture and a possible Perim Island seizure within ~19 days. The Polymarket anchor of 12.7% (no Kalshi price available) and a rising term structure (21.5% Oct 31, 28% Dec 31) indicate the market sees escalation risk as building beyond Sept 30 rather than imminent. I land slightly below the proxy at 10% given the short window, the lack of any confirmed reading near the threshold, and the need for a sustained 7-day collapse rather than a single-day dip like Aug 7.

gpt-5.6-sol

0% conf

Yes	50%
No	50%

uniform fallback: Expecting ',' delimiter: line 13 column 3 (char 899)

5. Devil's Advocate Sonnet 5 · red-team critique

Forecast 2 is a degenerate fallback (uniform 50/50 with confidence=0.00) that produced a JSON parsing error—it contains no actual analysis of the evidence and should be disregarded as uninformative, not treated as a genuine competing view.

Forecast 1's 10% lands below the Polymarket anchor of 12.7% without fully justifying the discount; given that Polymarket already reflects the Sept 10-11 Mocha escalation (the brief notes it's "up sharply... reflecting the Sept 10-11 escalation"), and the analyst model's blended range is 5-15%, landing at 10% is defensible but the rationale doesn't explain why it should sit below rather than at/above the market anchor.

Neither forecast adequately grapples with the 7-day MA mechanics given the Aug 7 single-day collapse to "a single dry bulk carrier": if a Perim Island seizure or full blockade attempt occurs even briefly in the remaining ~19 days, a sustained multi-day disruption could plausibly drag a 7-day average below 10 given that volatility was already demonstrated once, and this scenario deserves more explicit weighting rather than being waved off as "single-day dip."

Forecast 1 doesn't engage with the term-structure detail that Oct 31 pricing (21.5%) is not dramatically higher than Sept 30 implied risk — a rising-but-not-steep term structure could equally suggest the market sees a meaningful near-term tail risk that persists/grows, not necessarily that Sept 30 risk is negligible; the "escalation is later" reading is one interpretation but not the only one.

Both forecasts underweight the compounding/conditional nature of the Mocha capture: it is a confirmed, discrete, very recent event (Sept 10-11, just before close) that materially changes the Perim Island seizure probability, yet Forecast 1 treats it as already priced-in via Polymarket without independently assessing whether a fast-moving offensive could outpace market pricing in a thin ~20-day window.

Neither forecast discusses the asymmetry that PortWatch data itself may lag real-world events (data-reporting delay), meaning even a genuine closure event in mid-to-late September might not be reflected/confirmed in the dataset by Sept 30, which could argue for a lower Yes probability than the "real-world" blockade risk alone would suggest — this measurement-lag consideration is a gap in both analyses.

6. Aggregator Fable 5.1 · final calibrated forecast

11% (26% confidence)

Yes: 11% No: 89%

Forecast 2 is a degenerate 50/50 fallback with zero confidence and no analysis, so it is disregarded. Forecast 1's reasoning holds: late-August transits of ~27-35/day are ~3x the ≤10 PortWatch 7-day-MA threshold, carriers were still phasing back into the Suez corridor, and the 2024-2025 campaign trough never approached 10/day, so a Yes requires a sustained multi-day collapse triggered by a full blockade (e.g., Perim Island seizure) within a ~19-day window. The critique correctly notes the Mocha capture materially raises tail risk and the Aug 7 single-day collapse shows traffic can crater quickly, which argues against discounting far below the Polymarket anchor of 12.7%; however, the rising term structure (21.5% Oct 31, 28% Dec 31) and possible PortWatch reporting lag argue against going above it. I settle at 11% Yes, essentially at the market-implied level with a slight haircut for the short window and measurement mechanics.

Pipeline Timing

Total pipeline time: 321.4s

Per-tool research timings shown in the Research section above.