Scan: Will OpenAI have a #1 AI model by December 31, 2026?

date	predicted	market price	confidence
2026-09-06	34%	30%	55%
2026-08-30	27%	28%	56%
2026-08-14	36%	34%	53%

1. Planner Fable 5.1 · Fermi decomposition + tool plan

Tools chosen: polymarket_direct resolution_source polymarket_related kalshi_related article_search claude_news wikipedia

Sub-questions (Fermi decomposition)

Which company currently holds #1 on the LMArena Text Arena Overall leaderboard with style control off, and how large is the Elo gap to OpenAI's best model?
Over the past 18-24 months, what share of the time has an OpenAI model held or tied for #1 on the LMArena text leaderboard, and how often has the top spot changed hands?
What frontier models is OpenAI expected to release before December 31, 2026 (e.g., GPT-5.x/GPT-6), and what is their expected timing relative to Google, Anthropic, and xAI releases?
How do LMArena's tie rules (overlapping confidence intervals sharing rank 1) work in practice, and how often are multiple companies tied at rank #1 with style control off?
What do the sibling Polymarket markets (Google, Anthropic, xAI, Meta, DeepSeek) imply about the total probability mass, and is it consistent with the OpenAI price?
Are there any planned changes to the LMArena leaderboard methodology or availability that could affect how the 'style control off' overall ranking is displayed by end of 2026?

Planner reasoning

This is a Polymarket question about whether OpenAI tops the LMArena text leaderboard (style control off) at end of 2026. Key drivers are the current leaderboard state, the historical churn of the #1 spot among OpenAI/Google/Anthropic/xAI, and OpenAI's release pipeline through late 2026. The market price and resolution page are the primary anchors; news on upcoming frontier model releases and competitor positioning fills in the rest.

2. Research Parallel tool calls

tool	status	time	items	summary
polymarket_direct	OK	0.5s	1	## This Market's Polymarket Data Will OpenAI have a #1 AI model by December 31, 2026? - Current price (probability): 27.50% - 7-day price change: -8.00% - 30-day price change: -5.00% - Total volume: $30,306 (USD notional) - Price range: 16.50% - 40.50% - Data points: 90 days
resolution_source	OK	4.8s	1	already_resolved=no; matches_criteria=True; last_updated=Sep 13, 2026. The leaderboard's #1 ranked model as of Sep 13, 2026 is Anthropic's claude-fable-5 (score 1506), not an OpenAI model; OpenAI's highest-ranked model shown is gpt-5.6-sol-xhigh at rank 18 (score 1483).
polymarket_related	OK	0.6s	18	Polymarket search over 4 keyword(s), kept 18 matches. keyword '#1 AI model': 8 markets \| keyword 'lmarena': 0 markets \| keyword 'Chatbot Arena': 8 markets \| keyword 'top AI model December 31': 2 markets
kalshi_related	OK	2.3s	0	0 related markets / summaries. keyword 'best AI model': no matches \| keyword 'lmarena': no matches \| keyword 'chatbot arena': no matches
article_search	OK	0.8s	32	Fetched 32 unique articles across 4 queries (lookback=60d). 'LMArena leaderboard top model OpenAI Google Gemini': 10 articles \| 'OpenAI next frontier model release 2026': 10 articles \| 'Gemini 3 Claude GPT leaderboard rankings': 10 articles \| 'LMArena style control ranking methodology change': 10 ar
claude_news	OK	33.3s	16	Here are the key findings from research (note: several third-party leaderboard-tracking sites give conflicting snapshots, which itself signals how volatile/contested the "#1" spot is in 2026 — treat exact current rank with caution): Current LMArena standings (as of Sept 2026, sources conflict)
wikipedia	OK	0.5s	3	Fetched 3 Wikipedia entries (0 missing pages).

3. Evidence Brief Sonnet 5 · 7630 chars

# Current state As of the most recent resolution-source check (Sep 13, 2026), OpenAI does NOT hold #1 on the LMArena Text Arena Overall leaderboard (style control off); Anthropic's claude-fable-5 leads (1506) while OpenAI's best model (gpt-5.6-sol-xhigh) sits at rank 18 (1483). The market resolves on the leaderboard's status at Dec 31, 2026, so today's snapshot is not final — OpenAI has since released GPT-6 Astra (Sep 3, 2026) whose LMArena position is not yet clearly confirmed as #1 in independent trackers. # Timeline of key events - 2025-08-07: GPT-5 launched (confirmed, Wikipedia). - 2026-07 (mid): Google's Gemini 3.5 Pro flagship reported delayed past original June target; Google ships cheaper Flash-tier models instead (confirmed, CNBC). - 2026-07 (~mid-late): OpenAI releases GPT-5.6 family (Sol, Terra, Luna) as new flagship, positioned as SOTA on intelligence/efficiency (confirmed, OpenAI.com). - 2026-07-12: Third-party tracker reports Arena re-baselined Claude Fable scoring after a July 1 "restoration," after which Claude Fable regained top spot (reported, localaimaster.com). - 2026-08-12: Google DeepMind leadership change (Kavukcuoglu promoted); analysts frame Google as still catching up to OpenAI/Anthropic (confirmed, CNBC). - 2026-09-02: Analyst commentary (D.A. Davidson) says Google remains "distant third" behind Anthropic/OpenAI in enterprise (reported, CNBC). - 2026-09-03: OpenAI launches GPT-6 Astra, claimed as its most capable/aligned model, with strong self-reported benchmarks (FrontierMath, ARC-AGI-3, ExploitBench) but LMArena rank not independently confirmed as #1 (reported, multiple trackers). - 2026-09-13: Resolution-source snapshot shows Anthropic's claude-fable-5 at #1 (1506); OpenAI's top model ranked #18 (1483) (confirmed, direct leaderboard check). - Ongoing (Sep 2026): Multiple third-party leaderboard mirrors disagree on exact #1 (Claude Fable 5, Claude Opus 4.6/4.7/4.8, Grok-4.1 Thinking all cited as leading in different snapshots), reflecting a tightly clustered top-tier with sub-25-50 Elo gaps (reported, various aggregators). # Event Will OpenAI hold the #1 rank (or tie for it) on the LMArena Text Arena Overall leaderboard (style control off) as of Dec 31, 2026? # Outcomes to forecast Yes / No # Kalshi market anchor No direct Kalshi price returned (kalshi_related found 0 matches); Polymarket sibling market on the same underlying event shows **YES 27.5%**, down 8pts in 7 days and 5pts in 30 days, range 16.5%–40.5% over 90 days, volume ~$30.3k. Treat this Polymarket price as the best available consensus anchor in absence of native Kalshi data. # Resolution source Fetched https://arena.ai/leaderboard/text (per tool; description references lmarena.ai) — as of Sep 13, 2026, #1 is Anthropic's claude-fable-5 (1506); OpenAI's best model gpt-5.6-sol-xhigh ranks #18 (1483). Condition currently unmet (already_resolved=no); market stays open until Dec 31, 2026, so status can still change. # Sub-question answers 1. **Who's #1 now, and gap to OpenAI?** Per direct resolution check: Anthropic's claude-fable-5 (#1, 1506) vs. OpenAI's best at #18 (1483) — a 23-point gap, but third-party trackers conflict (Grok-4.1 Thinking, Claude Opus variants also cited as leading), reflecting a tightly bunched top tier within ~20-50 Elo (claude_news). 2. **Historical share of time at #1 (18-24mo)?** One aggregator (benchlm.ai) states OpenAI held #1 for 15/41 months (~37%) historically — the most of any lab — vs. Anthropic (9mo) and Google (8mo); crown has changed hands 19 times since May 2023, indicating high turnover. 3. **Upcoming OpenAI releases vs. rivals?** OpenAI shipped GPT-5.6 (Sol/Terra/Luna) in July 2026, then GPT-6 Astra on Sep 3, 2026, explicitly built to respond to Anthropic's Fable/Mythos family. Google's Gemini 3.5 Pro was delayed past June 2026 and Gemini 4 is in early compute investment; xAI's Grok-4.1 also intermittently competitive (claude_news, CNBC). 4. **Tie rules/frequency of ties?** Description confirms ties (overlapping CIs) suffice for YES. No specific data found on how often multi-way #1 ties with style-control-off occur; research is silent on quantified tie frequency — flagged gap. 5. **Sibling Polymarket markets — total mass consistent?** Google 30%, OpenAI 27.5%, xAI 12.5%, Alibaba 7%, Moonshot 8.5%, Baidu 6.5%, ByteDance 0.9%, Amazon 3.25%. Sum ≈ 96% (before Anthropic/Meta/DeepSeek, not shown), roughly consistent with a near-fully-allocated multi-way race; Anthropic-specific sibling market not in results but qualitative evidence (claude_news, resolution_source) suggests Anthropic is currently strongest, implying its implied price is likely highest, which is plausible if OpenAI's 27.5% and Google's 30% leave room for Anthropic ~25-35%. 6. **LMArena methodology changes?** Reported re-baselining event around July 1, 2026 ("restoration") affecting Claude Fable's score is the only cited change; no confirmed structural methodology overhaul found. Research is silent on further planned changes through 2026. # Key facts (high-confidence, factual) 1. [resolution_source] Sep 13, 2026 snapshot: Anthropic #1, OpenAI best model rank #18. 2. [polymarket_direct] Sibling market YES=27.5%, declining trend. 3. [wikipedia] GPT-5 launched Aug 7, 2025; ties allowed per market rules. 4. [claude_news/OpenAI.com] GPT-5.6 (Jul 2026) and GPT-6 Astra (Sep 3, 2026) are OpenAI's latest frontier releases. 5. [CNBC] Google's Gemini 3.5 Pro delayed past June 2026; Gemini 4 still in development. # Cross-market signals - Kalshi related: none found. - Polymarket: OpenAI 27.5% (falling), Google 30%, xAI 12.5%, various China labs low single digits — implies market sees OpenAI as a strong-but-not-favorite contender behind Google/Anthropic in a fragmented multi-way race. - Sportsbook implied: N/A. # Analyst opinions and speculation - D.A. Davidson analyst: Google is "distant third" behind Anthropic/OpenAI in enterprise (Sep 2026), suggesting OpenAI still viewed as top-tier contender despite current arena rank slip. - Multiple trackers (claude_news synthesis): top-tier Elo gaps now within noise (~20-50 points), meaning any new release (including GPT-6 Astra) could flip #1 quickly; "genuinely contested" through year-end. # Directional lean per outcome - **Yes**: OpenAI's historical plurality (37% of months at #1, most of any lab); newly launched GPT-6 Astra explicitly built to leapfrog rivals; frequent crown changes (19x in ~3.5yrs) mean OpenAI has good odds of regaining #1 before Dec 31. - **No**: Current snapshot (Sep 13) shows OpenAI far from #1 (rank 18); Polymarket price falling (27.5%, down from 40.5% high); Anthropic's Claude Fable/Opus line and Google's Gemini currently at/near top in most trackers; extreme top-tier clustering means any lab, not necessarily OpenAI, could hold #1 at year-end. # Gaps / unknowns - No live Kalshi price found for this specific ticker (relied on Polymarket sibling). - Conflicting third-party leaderboard snapshots create uncertainty about true current #1. - No data on GPT-6 Astra's actual LMArena placement post-launch. - No quantified frequency of multi-way ties under style-control-off rule. - Anthropic's own sibling Polymarket price not retrieved for cross-check. # Calibration anchors - Polymarket YES price (proxy anchor): 27.5%, recent downtrend (-8% 7d, -5% 30d). - Historical base rate: OpenAI #1 ~37% of months over past ~3.5 years, but currently not #1 with ~3.5 months to resolution and frequent hand-offs (19 changes in 41 months, ~1 every 2 months) — suggests meaningful but sub-50% probability of holding #1 specifically at the Dec 31, 2026 snapshot.

4. Forecasters 5 draws · Fable 5.1 + GPT-5.6 Sol

claude-fable-5-1

46% conf

Yes	28%
No	72%

The resolution source (Sep 13, 2026) shows Anthropic's claude-fable-5 at #1 with OpenAI's best model at rank 18, 23 Elo behind, and the Polymarket sibling anchor sits at 27.5% YES on a downtrend. Offsetting factors are that ties (overlapping CIs) count as YES, the top tier is clustered within noise, the crown has changed hands ~19 times in 41 months, OpenAI historically held #1 ~37% of months, and GPT-6 Astra (Sep 3) has not yet clearly registered on the board and could climb. With ~3.5 months left and a multi-way race where Google and Anthropic are at least as likely to hold #1 at the snapshot, a probability near the market anchor is appropriate, nudged slightly for OpenAI's release cadence and the tie rule.

claude-fable-5-1

45% conf

Yes	25%
No	75%

The resolution-source snapshot (Sep 13, 2026) shows OpenAI's best model at rank 18, 23 Elo behind Anthropic's claude-fable-5, and notably GPT-6 Astra (launched Sep 3) has not surfaced as #1 ten days post-launch, which undercuts the main bullish catalyst. The Polymarket sibling price of 27.5% (down 8pts in a week, off a 40.5% high) is the best consensus anchor and already prices OpenAI's historical ~37% share of months at #1 plus the tie-allowed rule and frequent crown turnover. Offsetting factors—a possible further OpenAI release before Dec 31 and a tightly clustered top tier—keep this meaningfully above single digits, but Google's pending Gemini 3.5 Pro and Anthropic's current lead mean competition for the year-end slot is multi-way. I land slightly below the anchor at 25% given the weak Astra signal on the actual resolution source.

claude-fable-5-1

45% conf

Yes	26%
No	74%

The Sep 13, 2026 resolution-source snapshot shows Anthropic's claude-fable-5 at #1 (1506) with OpenAI's best model at rank 18 (1483), and GPT-6 Astra (launched Sep 3) has not yet displaced it, suggesting the new flagship did not immediately claim the crown. OpenAI's historical plurality (~37% of months at #1) and the frequent turnover (19 changes in 41 months) plus the tie-counts-as-YES rule keep meaningful upside, but with ~3.5 months left, a tightly clustered top tier where Google/Anthropic/xAI can also flip #1, and no confirmed Astra placement, OpenAI is a contender rather than the favorite. The Polymarket sibling anchor at 27.5% (declining) aligns with this multi-way-race picture; I shade slightly below it given the current 23-point deficit and the absence of Astra at the top.

gpt-5.6-sol

64% conf

Yes	28%
No	72%

The 27.5% Polymarket YES price is the best consensus anchor, and the direct Sep. 13 resolution-source snapshot favors No because Anthropic leads OpenAI by 23 Elo points, with OpenAI only at rank 18. Historical turnover and OpenAI's 37% share of months at #1 support meaningful comeback odds, especially because GPT-6 Astra's Arena performance remains unconfirmed and ties qualify for Yes. However, OpenAI has already deployed two recent frontier generations without a documented #1 placement, while several rival labs remain competitive in a tightly clustered field. I therefore stay close to the market anchor, raising YES only slightly to 28%.

gpt-5.6-sol

63% conf

Yes	28%
No	72%

The direct Sep. 13 resolution-source snapshot points toward No because Anthropic leads at 1506 while OpenAI's best listed model is rank 18 at 1483. Historical turnover and OpenAI's 37% share of months at #1 support meaningful Yes odds, while the recent GPT-6 Astra release and tie-friendly rules provide plausible paths to the top by year-end. However, Astra's actual LMArena placement is unconfirmed, rival models remain tightly clustered, and OpenAI has only about three and a half months to overtake them. I therefore remain close to the 27.5% Polymarket consensus anchor, raising Yes only slightly to 28%.

6. Final plain mean of 5 draws

27% (53% confidence)

Yes: 27% No: 73%

Mean of 5 draws (0.28, 0.25, 0.26, 0.28, 0.28). The resolution source (Sep 13, 2026) shows Anthropic's claude-fable-5 at #1 with OpenAI's best model at rank 18, 23 Elo behind, and the Polymarket sibling anchor sits at 27.5% YES on a downtrend. Offsetting factors are that ties (overlapping CIs) count as YES, the top tier is clustered within noise, the crown has changed hands ~19 times in 41 months, OpenAI historically held #1 ~37% of months, and GPT-6 Astra (Sep 3) has not yet clearly registered on the board and could climb. With ~3.5 months left and a multi-way race where Google and Anthropic are at least as likely to hold #1 at the snapshot, a probability near the market anchor is appropriate, nudged slightly for OpenAI's release cadence and the tie rule.

Pipeline Timing

Total pipeline time: 101.4s

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