Skip to main content

To trade in the US, go to polymarket.us

icon for Best AI model on September 21?
Tech·AI

Best AI model on September 21?

icon for Best AI model on September 21?
Tech·AI

Best AI model on September 21?

Sep 7

Sep 14

Sep 21

Sep 7

Sep 14

Sep 21

claude-fable-5.1-max 57%

Other 35%

claude-opus-5-high 3.5%

claude-opus-5-max 2.0%

Polymarket
NEW

claude-fable-5.1-max 57%

Other 35%

claude-opus-5-high 3.5%

claude-opus-5-max 2.0%

Polymarket
NEW

claude-fable-5.1-max

$2,960 Vol.

57%

Other

$2,499 Vol.

35%

claude-opus-5-high

$128 Vol.

4%

claude-opus-5-max

$347 Vol.

2%

claude-opus-4-6-high

$239 Vol.

1%

This market will resolve according to the model that has the highest arena rank based on the arena.ai Text Arena (Overall) when the table under the "Leaderboard" tab is checked on the specified date, 12:00 PM ET. Results from the "Rank" column under the "Text Arena | Overall" Leaderboard tab at https://arena.ai/leaderboard/text/overall-no-style-control with style control off (Adjustments: None) and filtered for "Models" will be used to resolve this market. Note: Models marked “AutoEval” at the applicable check time will not be considered, regardless of whether they display a rank or score. No new model will be added to this market after market creation. Any model not explicitly listed in this market will be encompassed under the "Other" option. Models will be ordered primarily by their leaderboard rank at the market’s check time. If two or more models are tied on rank, they will be ordered by their Arena score, including any underlying, unrounded, granular values reflected in the data below the leaderboard. If a tie still remains, alphabetical order of model names as listed in this market group (full string, including suffixes such as “-high” and “-max”) will be used as a final tiebreaker (e.g., if two models remain tied, “claude-opus-5-high” would be ranked ahead of “claude-opus-5-max”). This market will resolve to the model that comes first according to this order. The resolution source for this market is the arena.ai Text Arena (Overall). If this resolution source is unavailable at check time, this market will remain open until the leaderboard comes back online and will resolve based on the first check after it becomes available. If it becomes permanently unavailable, this market will resolve to "Other".Anthropic’s September 1 release of Claude Fable 5.1-max has driven the 56.5% market-implied odds, as the upgrade delivers stronger long-horizon agentic coding, multistep research, and knowledge-work performance than prior Fable 5 or Opus tiers on benchmarks like Frontier-Bench and CursorBench. Traders view the model’s 1M-token context, adaptive thinking, and reduced safeguard friction as establishing a clear lead with just weeks until the September 21 resolution. Lower-priced Claude Opus 5 variants sit in single digits because they trail on peak capability despite cost advantages, while the 35.5% “Other” share reflects uncertainty over potential near-term releases from OpenAI or Google that could shift leaderboard rankings before the cutoff.

This market will resolve according to the model that has the highest arena rank based on the arena.ai Text Arena (Overall) when the table under the "Leaderboard" tab is checked on the specified date, 12:00 PM ET.

Results from the "Rank" column under the "Text Arena | Overall" Leaderboard tab at https://arena.ai/leaderboard/text/overall-no-style-control with style control off (Adjustments: None) and filtered for "Models" will be used to resolve this market.

Note: Models marked “AutoEval” at the applicable check time will not be considered, regardless of whether they display a rank or score.

No new model will be added to this market after market creation. Any model not explicitly listed in this market will be encompassed under the "Other" option.

Models will be ordered primarily by their leaderboard rank at the market’s check time. If two or more models are tied on rank, they will be ordered by their Arena score, including any underlying, unrounded, granular values reflected in the data below the leaderboard. If a tie still remains, alphabetical order of model names as listed in this market group (full string, including suffixes such as “-high” and “-max”) will be used as a final tiebreaker (e.g., if two models remain tied, “claude-opus-5-high” would be ranked ahead of “claude-opus-5-max”). This market will resolve to the model that comes first according to this order.

The resolution source for this market is the arena.ai Text Arena (Overall). If this resolution source is unavailable at check time, this market will remain open until the leaderboard comes back online and will resolve based on the first check after it becomes available. If it becomes permanently unavailable, this market will resolve to "Other".This market will resolve according to the model that has the highest arena rank based on the arena.ai Text Arena (Overall) when the table under the "Leaderboard" tab is checked on the specified date, 12:00 PM ET. Results from the "Rank" column under the "Text Arena | Overall" Leaderboard tab at https://arena.ai/leaderboard/text/overall-no-style-control with style control off (Adjustments: None) and filtered for "Models" will be used to resolve this market. Note: Models marked “AutoEval” at the applicable check time will not be considered, regardless of whether they display a rank or score. No new model will be added to this market after market creation. Any model not explicitly listed in this market will be encompassed under the "Other" option. Models will be ordered primarily by their leaderboard rank at the market’s check time. If two or more models are tied on rank, they will be ordered by their Arena score, including any underlying, unrounded, granular values reflected in the data below the leaderboard. If a tie still remains, alphabetical order of model names as listed in this market group (full string, including suffixes such as “-high” and “-max”) will be used as a final tiebreaker (e.g., if two models remain tied, “claude-opus-5-high” would be ranked ahead of “claude-opus-5-max”). This market will resolve to the model that comes first according to this order. The resolution source for this market is the arena.ai Text Arena (Overall). If this resolution source is unavailable at check time, this market will remain open until the leaderboard comes back online and will resolve based on the first check after it becomes available. If it becomes permanently unavailable, this market will resolve to "Other".
Volume
$6,173
End Date
Sep 21, 2026
Market Opened
Sep 3, 2026, 10:16 AM ET

Resolver

0x69c47De9D...
This market will resolve according to the model that has the highest arena rank based on the arena.ai Text Arena (Overall) when the table under the "Leaderboard" tab is checked on the specified date, 12:00 PM ET. Results from the "Rank" column under the "Text Arena | Overall" Leaderboard tab at https://arena.ai/leaderboard/text/overall-no-style-control with style control off (Adjustments: None) and filtered for "Models" will be used to resolve this market. Note: Models marked “AutoEval” at the applicable check time will not be considered, regardless of whether they display a rank or score. No new model will be added to this market after market creation. Any model not explicitly listed in this market will be encompassed under the "Other" option. Models will be ordered primarily by their leaderboard rank at the market’s check time. If two or more models are tied on rank, they will be ordered by their Arena score, including any underlying, unrounded, granular values reflected in the data below the leaderboard. If a tie still remains, alphabetical order of model names as listed in this market group (full string, including suffixes such as “-high” and “-max”) will be used as a final tiebreaker (e.g., if two models remain tied, “claude-opus-5-high” would be ranked ahead of “claude-opus-5-max”). This market will resolve to the model that comes first according to this order. The resolution source for this market is the arena.ai Text Arena (Overall). If this resolution source is unavailable at check time, this market will remain open until the leaderboard comes back online and will resolve based on the first check after it becomes available. If it becomes permanently unavailable, this market will resolve to "Other".Anthropic’s September 1 release of Claude Fable 5.1-max has driven the 56.5% market-implied odds, as the upgrade delivers stronger long-horizon agentic coding, multistep research, and knowledge-work performance than prior Fable 5 or Opus tiers on benchmarks like Frontier-Bench and CursorBench. Traders view the model’s 1M-token context, adaptive thinking, and reduced safeguard friction as establishing a clear lead with just weeks until the September 21 resolution. Lower-priced Claude Opus 5 variants sit in single digits because they trail on peak capability despite cost advantages, while the 35.5% “Other” share reflects uncertainty over potential near-term releases from OpenAI or Google that could shift leaderboard rankings before the cutoff.

This market will resolve according to the model that has the highest arena rank based on the arena.ai Text Arena (Overall) when the table under the "Leaderboard" tab is checked on the specified date, 12:00 PM ET.

Results from the "Rank" column under the "Text Arena | Overall" Leaderboard tab at https://arena.ai/leaderboard/text/overall-no-style-control with style control off (Adjustments: None) and filtered for "Models" will be used to resolve this market.

Note: Models marked “AutoEval” at the applicable check time will not be considered, regardless of whether they display a rank or score.

No new model will be added to this market after market creation. Any model not explicitly listed in this market will be encompassed under the "Other" option.

Models will be ordered primarily by their leaderboard rank at the market’s check time. If two or more models are tied on rank, they will be ordered by their Arena score, including any underlying, unrounded, granular values reflected in the data below the leaderboard. If a tie still remains, alphabetical order of model names as listed in this market group (full string, including suffixes such as “-high” and “-max”) will be used as a final tiebreaker (e.g., if two models remain tied, “claude-opus-5-high” would be ranked ahead of “claude-opus-5-max”). This market will resolve to the model that comes first according to this order.

The resolution source for this market is the arena.ai Text Arena (Overall). If this resolution source is unavailable at check time, this market will remain open until the leaderboard comes back online and will resolve based on the first check after it becomes available. If it becomes permanently unavailable, this market will resolve to "Other".This market will resolve according to the model that has the highest arena rank based on the arena.ai Text Arena (Overall) when the table under the "Leaderboard" tab is checked on the specified date, 12:00 PM ET. Results from the "Rank" column under the "Text Arena | Overall" Leaderboard tab at https://arena.ai/leaderboard/text/overall-no-style-control with style control off (Adjustments: None) and filtered for "Models" will be used to resolve this market. Note: Models marked “AutoEval” at the applicable check time will not be considered, regardless of whether they display a rank or score. No new model will be added to this market after market creation. Any model not explicitly listed in this market will be encompassed under the "Other" option. Models will be ordered primarily by their leaderboard rank at the market’s check time. If two or more models are tied on rank, they will be ordered by their Arena score, including any underlying, unrounded, granular values reflected in the data below the leaderboard. If a tie still remains, alphabetical order of model names as listed in this market group (full string, including suffixes such as “-high” and “-max”) will be used as a final tiebreaker (e.g., if two models remain tied, “claude-opus-5-high” would be ranked ahead of “claude-opus-5-max”). This market will resolve to the model that comes first according to this order. The resolution source for this market is the arena.ai Text Arena (Overall). If this resolution source is unavailable at check time, this market will remain open until the leaderboard comes back online and will resolve based on the first check after it becomes available. If it becomes permanently unavailable, this market will resolve to "Other".
Volume
$6,173
End Date
Sep 21, 2026
Market Opened
Sep 3, 2026, 10:16 AM ET

Resolver

0x69c47De9D...

Related

icon for Will any other model be the best AI model on September 7, 2026?

Will any other model be the best AI model on September 7, 2026?

96%
icon for Will claude-fable-5.1-max be the best AI model on September 14, 2026?

Will claude-fable-5.1-max be the best AI model on September 14, 2026?

63%
icon for Will the next Claude Opus model debut at a score of at least 1500 by December 31, 2026?

Will the next Claude Opus model debut at a score of at least 1500 by December 31, 2026?

80%

Beware of external links.

Frequently Asked Questions

"Best AI model on September 21?" is a prediction market on Polymarket with 5 possible outcomes where traders buy and sell shares based on what they believe will happen. The current leading outcome is "claude-fable-5.1-max" at 57%, followed by "Other" at 35%. Prices reflect real-time crowd-sourced probabilities. For example, a share priced at 57¢ implies that the market collectively assigns a 57% chance to that outcome. These odds shift continuously as traders react to new developments and information. Shares in the correct outcome are redeemable for $1 each upon market resolution.

"Best AI model on September 21?" is a newly created market on Polymarket, launched on Sep 3, 2026. As an early market, this is your opportunity to be among the first traders to set the odds and establish the market's initial price signals. You can also bookmark this page to track volume and trading activity as the market gains traction over time.

To trade on "Best AI model on September 21?," browse the 5 available outcomes listed on this page. Each outcome displays a current price representing the market's implied probability. To take a position, select the outcome you believe is most likely, choose "Yes" to trade in favor of it or "No" to trade against it, enter your amount, and click "Trade." If your chosen outcome is correct when the market resolves, your "Yes" shares pay out $1 each. If it's incorrect, they pay out $0. You can also sell your shares at any time before resolution if you want to lock in a profit or cut a loss.

The current frontrunner for "Best AI model on September 21?" is "claude-fable-5.1-max" at 57%, meaning the market assigns a 57% chance to that outcome. The next closest outcome is "Other" at 35%. These odds update in real-time as traders buy and sell shares, so they reflect the latest collective view of what's most likely to happen. Check back frequently or bookmark this page to follow how the odds shift as new information emerges.

The resolution rules for "Best AI model on September 21?" define exactly what needs to happen for each outcome to be declared a winner — including the official data sources used to determine the result. You can review the complete resolution criteria in the "Rules" section on this page above the comments. We recommend reading the rules carefully before trading, as they specify the precise conditions, edge cases, and sources that govern how this market is settled.