Scan: Will the next Claude Opus model be released by September 30, 2026?

1. Planner Fable 5.1 · Fermi decomposition + tool plan

Tools chosen: polymarket_direct polymarket_related kalshi_related article_search claude_news gdelt_news wikipedia code_execution

Sub-questions (Fermi decomposition)

What is the most recent Claude Opus model released to the public, and on what date was it released?
What has been the historical gap (in days) between consecutive Opus-branded releases (Opus 3, Opus 4, 4.1, 4.5, etc.), and what base rate does that imply for a new Opus within the window ending Sept 30, 2026?
Are there credible leaks, reports, or Anthropic statements (e.g., The Information, Bloomberg, API/console strings, model IDs) pointing to a new Opus model launching in August or September 2026?
Is Anthropic's next flagship expected to carry the 'Opus' name, or is there evidence of a rebrand (e.g., 'Mythos', 'Claude 5' without Opus) that would disqualify the release?
Are there scheduled Anthropic events, developer conferences, or competitive pressures (OpenAI/Google launches) in Aug-Sep 2026 that historically coincide with Opus launches?
What do the Polymarket price history and any related Kalshi/Polymarket markets (e.g., 'Claude 5 by X date', 'best AI model end of Q3') imply about the probability?

Planner reasoning

The question hinges on Anthropic's release cadence and whether a new Opus-branded model ships in the roughly two-month window before Sept 30, 2026. Key uncertainties are the date of the most recent Opus release, historical inter-release gaps, credible leaks/rumors about the next flagship, and the naming risk (Mythos/other names not qualifying). Market prices on Polymarket and Kalshi provide the primary anchor and cross-check.

2. Research Parallel tool calls

tool	status	time	items	summary
polymarket_direct	OK	0.4s	1	## This Market's Polymarket Data Will the next Claude Opus model be released by September 30, 2026? - Current price (probability): 77.50% - 7-day price change: -1.50% - 30-day price change: +40.00% - Total volume: $42,441 (USD notional) - Price range: 34.00% - 86.50% - Data points: 26 days
polymarket_related	OK	3.3s	0	Scanned 100 active Polymarket markets, kept 0 matches. keyword 'Claude Opus': 0 markets \| keyword 'Anthropic': 0 markets \| keyword 'Claude 5': 0 markets \| keyword 'Mythos': 0 markets
kalshi_related	OK	3.2s	1	1 related markets / summaries. keyword 'Anthropic': ok \| keyword 'Claude': no matches \| keyword 'Opus': no matches
article_search	OK	4.5s	16	Fetched 16 unique articles across 4 queries (lookback=45d). 'Anthropic next Claude Opus model release': 10 articles \| 'Claude Opus 5 launch': 10 articles \| 'Anthropic Mythos model release': 10 articles \| 'Anthropic new flagship model leak': 10 articles
claude_news	OK	20.8s	8	## Findings - Most recent confirmed Claude Opus release before 2026 escalation: Claude Opus 4.5 launched November 24, 2025, as Opus 4.5 is available today on our apps, our API, and on all three major cloud platforms , priced at $5/$25 per million tokens. (anthropic.com) - **Anthropic then ite
gdelt_news	OK	153.0s	10	GDELT: 10 articles across 3 queries (lookback=30d). 'Anthropic Claude Opus release': error GDELT rate-limited after retries (429) \| 'Anthropic new model Mythos': 10 hits \| 'Claude 5 release date': error GDELT rate-limited after retries (429)
wikipedia	OK	0.1s	2	Fetched 2 Wikipedia entries (0 missing pages).
code_execution	OK	33.1s	0	## Key Findings - Historical inter-release gaps (Opus family): 444 days (Claude 3 Opus → Opus 4), 75 days (Opus 4 → Opus 4.1), 111 days (Opus 4.1 → Opus 4.5). Mean gap ≈ 210 days, median ≈ 111 days — but note the 444-day gap reflects a major-generation jump (Claude 3→4), while 75/111 days refle

3. Evidence Brief Sonnet 5 · 6818 chars

# Current state As of the latest research (through 2026-09-11), Anthropic's flagship line has bifurcated: "Opus" remains a distinct tier, but Anthropic's true top-of-stack models are now branded "Mythos"/"Fable" (Mythos 5, Fable 5, then Fable 5.1/Mythos 5.1 released Sept 1, 2026). The most recent Opus-branded release is **Claude Opus 5**, launched **July 24, 2026** — already publicly available on Claude, Claude Code, API, Bedrock, Vertex AI, and Foundry. Because the Kalshi rules explicitly list "Opus 5.1" as a qualifying *future* example, the market appears to treat Opus 5 as already-existing at question creation, meaning the resolving event is a **further** Opus release (5.1, 5.5, Opus 6, etc.) after Opus 5. No such successor has been reported as of Sept 11, 2026; recent Anthropic energy has gone into Mythos/Fable 5.1, not a new Opus. # Timeline of key events - 2025-11-24: Claude Opus 4.5 released publicly (confirmed, anthropic.com) - 2026-01 (approx.): Early Claude Opus 4.6 in use internally, later disclosed in Sept cybersecurity report (reported, CBS News 2026-09-09) - 2026-04 (approx.): Opus 4.7 in use, incident dated to April, disclosed later (reported, CBS News 2026-07-30/08-05) - 2026-05-28: Claude Opus 4.8 released, upgrade over 4.7 (confirmed, anthropic.com) - 2026-06: Claude Fable 5 (public, "Mythos-class") and Claude Mythos 5 (restricted) released — new top tier above Opus (confirmed, Wikipedia) - 2026-07-23: Leaked strings ("claude-opus-5-thinking-high", codename "Honeycomb") in Cursor/Vertex quotas (rumored, emergent.sh) - 2026-07-24: **Claude Opus 5 officially released**, publicly available across all major platforms (confirmed, Axios, evolink.ai, Fortune) - 2026-07-30: Anthropic discloses Opus 4.7 and Mythos 5 internet-access incidents (confirmed, CBS News) - 2026-08-27: Anthropic announces hardware/agent standard (MHS); no new Opus mentioned (confirmed, CNBC) - 2026-09-01: Claude Fable 5.1 and Mythos 5.1 released — most advanced models to date, but not Opus-branded (confirmed, CNBC/GDELT/TOI) - 2026-09-09/11: Opus 4.6 internet-access incident disclosed; EU given Mythos access (confirmed) — no mention of new Opus version # Event Will Anthropic release its *next* Opus-branded model (beyond Opus 5) to the general public by September 30, 2026? # Outcomes to forecast - Yes - No # Kalshi market anchor Polymarket-sourced pricing for this exact market (same ticker): **77.5% YES**, down 1.5pp over 7 days but up +40pp over 30 days (price range 34%–86.5% over 26 data points, ~$42.4K volume). The large 30-day jump strongly suggests repricing around the confirmed Opus 5 release news. No native Kalshi order book data was returned; no other Kalshi/Polymarket markets directly reference "Opus," "Claude," or "Mythos" release timing. # Sub-question answers 1. **Most recent Opus release/date** — Claude Opus 5, released 2026-07-24, publicly available (Axios, evolink.ai). Prior to that: Opus 4.8 (2026-05-28), Opus 4.7 (~April 2026), Opus 4.6 (~Jan 2026), Opus 4.5 (2025-11-24). 2. **Historical gaps** — Opus 3→4: 444 days; 4→4.1: 75 days; 4.1→4.5: 111 days; 4.5→4.8 chain (via 4.6/4.7): ~185 days; 4.8→Opus 5: 57 days. Code-execution model gives a wide 25%–97% conditional-probability range depending on whether the long generational gap or the fast minor-version cadence is used; blended point estimate ~50–65% for a release within a ~68-day window (Opus5→Sept30). 3. **Leaks/reports of Aug–Sep 2026 Opus launch** — None found; only Opus 5 leaks (pre-July 24) exist. Post-Opus 5, all confirmed reporting concerns Fable/Mythos 5.1 (Sept 1, 2026), not a new Opus. 4. **Naming/rebrand risk** — Confirmed structural shift: Anthropic's true flagship tier is now Mythos/Fable, with Opus as a secondary (still-updated) tier (Wikipedia, CBS News). This raises risk that Anthropic deprioritizes further Opus iteration in favor of Mythos/Fable branding. 5. **Events/competitive pressure** — GPT-6 launch noted same week as Fable/Mythos 5.1 (CNET, 2026-09-03), indicating competitive cadence, but no Anthropic developer conference specifically tied to Opus timing found. 6. **Cross-market signals** — Polymarket price for this exact market: 77.5%. No related Polymarket/Kalshi markets on "Claude 5" or Mythos found. Adjacent Kalshi market ("OpenAI or Anthropic IPO first – Anthropic," 93%) shows no direct relevance. # Key facts (high-confidence, factual) 1. [anthropic.com] Opus 4.5 released 2025-11-24; Opus 4.8 released 2026-05-28. 2. [Axios/evolink.ai] Opus 5 released 2026-07-24, publicly available across all platforms. 3. [Wikipedia] Anthropic introduced a new top tier (Mythos/Fable) above Opus in mid-2026. 4. [CNBC/GDELT] Fable 5.1 and Mythos 5.1 released 2026-09-01; no accompanying new Opus version. 5. [CBS News] Opus 4.6/4.7 existed as intermediate internal/limited versions between 4.5 and 4.8. # Cross-market signals - Kalshi related: Only tangential Anthropic markets (IPO race, US equity stake) — no direct signal. - Polymarket: Same-market price 77.5%, up sharply post-Opus 5 news, suggesting traders view Opus 5 (or expectation of imminent 5.1) as strong evidence toward YES. - Sportsbook implied: N/A. # Analyst opinions and speculation - Quant/base-rate model (code_execution) flags high sensitivity to small sample; fast-cadence regime implies near-certain (>95%) further Opus release in a ~68-day window if Anthropic maintains 2026's rapid iteration pace (57–111 day gaps). - Slow/generational-regime model implies only ~25% probability, if Opus 5 is treated as a "new generation" needing a longer gap before next update (as Opus 4→4.5 took ~year-class time before minor iterations resumed). - Bifurcation of flagship branding into Mythos/Fable suggests Opus may now receive less frequent updates than in the Opus 4.x rapid-iteration era. # Directional lean per outcome - **Yes**: Fast 2026 Opus cadence (57–111 day gaps), strong competitive pressure (GPT-6, Astra), Polymarket pricing at 77.5% and rising post-Opus-5. - **No**: Anthropic's flagship attention has shifted to Mythos/Fable (two releases without a corresponding new Opus since July); no leaks/reports of Opus 5.1/6 as of Sept 11, 2026; only ~3 weeks remain in window. # Gaps / unknowns - Whether "next Opus" for resolution purposes means Opus 5 itself (already satisfied, →YES near-certain) or a successor to Opus 5 (unresolved, contested). - No confirmation of any Opus 5.1/6 roadmap or internal testing leaks post-July 2026. - Kalshi's own order book/volume not directly retrieved (only Polymarket cross-listing). # Calibration anchors - Kalshi/Polymarket current YES price (anchor): **77.5%** - Precedent: Opus minor-version gaps historically 57–111 days; a 68-day window (Opus5→Sept30) is within precedent but not guaranteed, especially amid branding shift toward Mythos/Fable.

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

claude-fable-5-1

33% conf

Yes	68%
No	32%

The Polymarket-sourced anchor sits at 77.5% YES, having jumped ~40pp around the confirmed July 24 Opus 5 release, which suggests many traders believe Opus 5 itself satisfies (or nearly satisfies) the resolution criteria. If instead a successor to Opus 5 is required, the case is much weaker: only ~3 weeks remain, no Opus 5.1/6 leaks exist as of Sept 11, and Anthropic's recent releases (Fable/Mythos 5.1 on Sept 1) went to the new flagship tier rather than Opus, so a fresh conditional estimate would be closer to 25–35%. The 2026 Opus cadence (57–111 day gaps) keeps a late-September Opus 5.1 plausible but far from certain. Blending the resolution ambiguity with the market anchor, I shade modestly below the market to ~68% YES.

gpt-5.6-sol

66% conf

Yes	31%
No	69%

The 57–111 day cadence for recent Opus updates makes another release by September 30 plausible, but the historical-gap evidence still spans regimes and points only weakly toward Yes. No post-Opus-5 leaks or launch reports have surfaced by September 11, while Anthropic instead released Fable 5.1 and Mythos 5.1 on September 1, pointing toward No given the short remaining window. The shift of flagship attention toward Mythos/Fable and absence of an Opus-linked event further favor No, despite competitive pressure from GPT-6. I discount the 77.5% YES market anchor substantially because its 40-point rise around the July 24 Opus 5 release suggests traders may be treating Opus 5 itself as qualifying, whereas the specified event requires a successor beyond Opus 5.

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

Both forecasters flag the critical ambiguity—whether Opus 5 itself satisfies resolution—but resolve it differently without adequately justifying their choice: Forecast 1 leans toward crediting the market's apparent belief that Opus 5 counts, while Forecast 2 discounts the market entirely, yet the brief explicitly states "Opus 5.1" is listed as the qualifying future example, meaning Opus 5 does NOT satisfy resolution; Forecast 2's reading is better supported by the actual rules but neither forecaster fully commits to this as settled rather than a coin-flip.

Given the brief's explicit rule text ("Kalshi rules explicitly list 'Opus 5.1' as a qualifying future example"), the 77.5% Polymarket anchor is likely a mispricing/lagging indicator from traders reacting to Opus 5 news without fully digesting the "successor required" framing—Forecast 1 still anchors at 68% (only 9.5pp below market) despite conceding this exact point, which is inconsistent with its own reasoning that the conditional probability is "closer to 25–35%."

Neither forecaster weights sub-question 5 (competitive pressure from GPT-6/Astra) as a scenario where Anthropic might rush an Opus 5.1 specifically to compete, despite the brief noting "GPT-6 launch noted same week as Fable/Mythos 5.1" — this could be a catalyst for an unexpected late-September Opus release that neither forecast explores as a tail-upside scenario.

Both underweight the branding-shift evidence as potentially decisive rather than merely directional: two consecutive flagship releases (Fable/Mythos 5, then 5.1) with zero corresponding Opus movement since July 24 suggests Opus may be on a slower, secondary-tier cadence now, which could justify a probability closer to Forecast 2's low end or even lower than 31%, given no leaks exist at all (unlike prior Opus transitions, which had leak precedent like "Honeycomb" for Opus 5).

The historical gap data is presented as bimodal (57-111 days fast cadence vs. ~444 days slow) but neither forecaster explicitly discusses that ALL fast-cadence gaps (57-111 days) occurred within the "Opus 4.x" minor-version family, whereas Opus 5 is a new major version launched alongside a tier bifurcation—this is a reference-class error: the more relevant comparison may be Opus 3→4 (444 days) or Opus 4→4.5 (a longer generational gap), not the shorter 4.x-internal cadences.

Forecast 1's confidence (0.33) and Forecast 2's confidence (0.66) diverge sharply despite both facing the same core ambiguity and comparable evidence quality—this asymmetry in stated confidence is not well justified by the rationale text, which reads similarly uncertain in both cases.

6. Aggregator Fable 5.1 · final calibrated forecast

60% (50% confidence)

Yes: 60% No: 40%

The rules cite 'Opus 5.1' as a qualifying example, so Opus 5 (released July 24) almost certainly does not resolve this; a successor is needed within ~3 weeks of the latest research date. However, the critique's 'mispricing' thesis is weakened by timing: the +40pp move occurred over the 30 days ending Sept 11, well after Opus 5's release, so traders appear to be pricing a successor (plausibly expecting an Opus 5.1 to follow Fable/Mythos 5.1, consistent with Anthropic's 57–111 day 2026 Opus cadence). Countervailing evidence — no Opus 5.1 leaks, flagship attention shifting to Mythos/Fable, and the short remaining window — justifies a meaningful discount from the 77.5% anchor. Balancing the market signal against the reference-class and branding-shift concerns, I land at roughly 60% Yes, between the two forecasts but closer to the market-informed view.

Pipeline Timing

Total pipeline time: 290.0s

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