Anthropic’s recent launches of Claude Fable 5.1 and Mythos 5.1, combined with rapid Claude Code tool updates through mid-September 2026, have reinforced its competitive edge in agentic web development and coding workflows on Code Arena’s WebDev leaderboard. These releases delivered measurable gains in long-horizon tasks, tool use, and frontend benchmarks, helping maintain Anthropic’s market-implied 72.5% probability of finishing second behind OpenAI. Google’s decision to grant internal engineers access to Claude Opus 5 further signals real-world developer preference. OpenAI’s Codex integrations and GPT-5.6 updates keep it in the lead at 25.6% implied odds for second place, but traders appear to view Anthropic’s specialized coding momentum as more durable through month-end.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · UpdatedAnthropic 73.0%
OpenAI 25.4%
Alibaba 2.5%
Moonshot <1%
$78,285 Vol.
$78,285 Vol.
Sep 30, 2026
Anthropic
73%
OpenAI
25%
Alibaba
2%
Moonshot
1%
SpaceXAI
1%
Tencent
<1%
Z.ai
<1%
Meta
<1%
ByteDance
<1%
MiniMax
<1%
<1%
Xiaomi
<1%
DeepSeek
<1%
Thinky
<1%
Poolside
<1%
Mistral
<1%
Anthropic 73.0%
OpenAI 25.4%
Alibaba 2.5%
Moonshot <1%
$78,285 Vol.
$78,285 Vol.
Sep 30, 2026
Anthropic
$17,856 Vol.
73%
OpenAI
$11,499 Vol.
25%
Alibaba
$17,542 Vol.
2%
Moonshot
$12,379 Vol.
1%
SpaceXAI
$2,537 Vol.
1%
Tencent
$1,977 Vol.
<1%
Z.ai
$2,097 Vol.
<1%
Meta
$1,709 Vol.
<1%
ByteDance
$3,054 Vol.
<1%
MiniMax
$598 Vol.
<1%
$1,766 Vol.
<1%
Xiaomi
$1,468 Vol.
<1%
DeepSeek
$1,022 Vol.
<1%
Thinky
$617 Vol.
<1%
Poolside
$1,035 Vol.
<1%
Mistral
$1,130 Vol.
<1%
This market will resolve according to the second-highest ranked Company based on the arena.ai Code Arena | WebDev Leaderboard when the table under "Code Arena | WebDev" filtered for "Labs" is checked on September 30, 2026, 12:00 PM ET.
Results from the "Lab Rank" column under the "Code Arena | WebDev" Leaderboard tab at https://arena.ai/leaderboard/code/webdev?rankBy=labs (Overall) filtered for "Labs" will be used to resolve this market.
AI companies will be ordered primarily by their Lab Rank at the market’s check time. If the results based on the lab ranking are ambiguous or unavailable, the relevant AI companies will be ordered according to their highest-ranking AI model in the leaderboard’s “Models” view. If two or more models are tied on rank, they will be ordered by which model is listed higher on the leaderboard. If a tie still remains, alphabetical order of AI lab/company names as listed in this market group will be used as a final tiebreaker (e.g., “Google” would be ranked ahead of “SpaceXAI”). This market will resolve based on the company that occupies second place under this ranking.
The resolution source for this market is the arena.ai Code Arena | WebDev Leaderboard. 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 recent launches of Claude Fable 5.1 and Mythos 5.1, combined with rapid Claude Code tool updates through mid-September 2026, have reinforced its competitive edge in agentic web development and coding workflows on Code Arena’s WebDev leaderboard. These releases delivered measurable gains in long-horizon tasks, tool use, and frontend benchmarks, helping maintain Anthropic’s market-implied 72.5% probability of finishing second behind OpenAI. Google’s decision to grant internal engineers access to Claude Opus 5 further signals real-world developer preference. OpenAI’s Codex integrations and GPT-5.6 updates keep it in the lead at 25.6% implied odds for second place, but traders appear to view Anthropic’s specialized coding momentum as more durable through month-end.
This market will resolve according to the second-highest ranked Company based on the arena.ai Code Arena | WebDev Leaderboard when the table under "Code Arena | WebDev" filtered for "Labs" is checked on September 30, 2026, 12:00 PM ET.
Results from the "Lab Rank" column under the "Code Arena | WebDev" Leaderboard tab at https://arena.ai/leaderboard/code/webdev?rankBy=labs (Overall) filtered for "Labs" will be used to resolve this market.
AI companies will be ordered primarily by their Lab Rank at the market’s check time. If the results based on the lab ranking are ambiguous or unavailable, the relevant AI companies will be ordered according to their highest-ranking AI model in the leaderboard’s “Models” view. If two or more models are tied on rank, they will be ordered by which model is listed higher on the leaderboard. If a tie still remains, alphabetical order of AI lab/company names as listed in this market group will be used as a final tiebreaker (e.g., “Google” would be ranked ahead of “SpaceXAI”). This market will resolve based on the company that occupies second place under this ranking.
The resolution source for this market is the arena.ai Code Arena | WebDev Leaderboard. 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".
Results from the "Lab Rank" column under the "Code Arena | WebDev" Leaderboard tab at https://arena.ai/leaderboard/code/webdev?rankBy=labs (Overall) filtered for "Labs" will be used to resolve this market.
AI companies will be ordered primarily by their Lab Rank at the market’s check time. If the results based on the lab ranking are ambiguous or unavailable, the relevant AI companies will be ordered according to their highest-ranking AI model in the leaderboard’s “Models” view. If two or more models are tied on rank, they will be ordered by which model is listed higher on the leaderboard. If a tie still remains, alphabetical order of AI lab/company names as listed in this market group will be used as a final tiebreaker (e.g., “Google” would be ranked ahead of “SpaceXAI”). This market will resolve based on the company that occupies second place under this ranking.
The resolution source for this market is the arena.ai Code Arena | WebDev Leaderboard. 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".
Market Opened: Jul 24, 2026, 7:45 PM ET
Volume
$78,285End Date
Oct 1, 2026Market Opened
Jul 24, 2026, 7:45 PM ETResolution Source
https://arena.ai/leaderboard/code/webdev?rankBy=labsResolver
0x69c47De9D...This market will resolve according to the second-highest ranked Company based on the arena.ai Code Arena | WebDev Leaderboard when the table under "Code Arena | WebDev" filtered for "Labs" is checked on September 30, 2026, 12:00 PM ET.
Results from the "Lab Rank" column under the "Code Arena | WebDev" Leaderboard tab at https://arena.ai/leaderboard/code/webdev?rankBy=labs (Overall) filtered for "Labs" will be used to resolve this market.
AI companies will be ordered primarily by their Lab Rank at the market’s check time. If the results based on the lab ranking are ambiguous or unavailable, the relevant AI companies will be ordered according to their highest-ranking AI model in the leaderboard’s “Models” view. If two or more models are tied on rank, they will be ordered by which model is listed higher on the leaderboard. If a tie still remains, alphabetical order of AI lab/company names as listed in this market group will be used as a final tiebreaker (e.g., “Google” would be ranked ahead of “SpaceXAI”). This market will resolve based on the company that occupies second place under this ranking.
The resolution source for this market is the arena.ai Code Arena | WebDev Leaderboard. 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 recent launches of Claude Fable 5.1 and Mythos 5.1, combined with rapid Claude Code tool updates through mid-September 2026, have reinforced its competitive edge in agentic web development and coding workflows on Code Arena’s WebDev leaderboard. These releases delivered measurable gains in long-horizon tasks, tool use, and frontend benchmarks, helping maintain Anthropic’s market-implied 72.5% probability of finishing second behind OpenAI. Google’s decision to grant internal engineers access to Claude Opus 5 further signals real-world developer preference. OpenAI’s Codex integrations and GPT-5.6 updates keep it in the lead at 25.6% implied odds for second place, but traders appear to view Anthropic’s specialized coding momentum as more durable through month-end.
This market will resolve according to the second-highest ranked Company based on the arena.ai Code Arena | WebDev Leaderboard when the table under "Code Arena | WebDev" filtered for "Labs" is checked on September 30, 2026, 12:00 PM ET.
Results from the "Lab Rank" column under the "Code Arena | WebDev" Leaderboard tab at https://arena.ai/leaderboard/code/webdev?rankBy=labs (Overall) filtered for "Labs" will be used to resolve this market.
AI companies will be ordered primarily by their Lab Rank at the market’s check time. If the results based on the lab ranking are ambiguous or unavailable, the relevant AI companies will be ordered according to their highest-ranking AI model in the leaderboard’s “Models” view. If two or more models are tied on rank, they will be ordered by which model is listed higher on the leaderboard. If a tie still remains, alphabetical order of AI lab/company names as listed in this market group will be used as a final tiebreaker (e.g., “Google” would be ranked ahead of “SpaceXAI”). This market will resolve based on the company that occupies second place under this ranking.
The resolution source for this market is the arena.ai Code Arena | WebDev Leaderboard. 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".
Results from the "Lab Rank" column under the "Code Arena | WebDev" Leaderboard tab at https://arena.ai/leaderboard/code/webdev?rankBy=labs (Overall) filtered for "Labs" will be used to resolve this market.
AI companies will be ordered primarily by their Lab Rank at the market’s check time. If the results based on the lab ranking are ambiguous or unavailable, the relevant AI companies will be ordered according to their highest-ranking AI model in the leaderboard’s “Models” view. If two or more models are tied on rank, they will be ordered by which model is listed higher on the leaderboard. If a tie still remains, alphabetical order of AI lab/company names as listed in this market group will be used as a final tiebreaker (e.g., “Google” would be ranked ahead of “SpaceXAI”). This market will resolve based on the company that occupies second place under this ranking.
The resolution source for this market is the arena.ai Code Arena | WebDev Leaderboard. 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
$78,285End Date
Oct 1, 2026Market Opened
Jul 24, 2026, 7:45 PM ETResolution Source
https://arena.ai/leaderboard/code/webdev?rankBy=labsResolver
0x69c47De9D...Anthropic’s recent launches of Claude Fable 5.1 and Mythos 5.1, combined with rapid Claude Code tool updates through mid-September 2026, have reinforced its competitive edge in agentic web development and coding workflows on Code Arena’s WebDev leaderboard. These releases delivered measurable gains in long-horizon tasks, tool use, and frontend benchmarks, helping maintain Anthropic’s market-implied 72.5% probability of finishing second behind OpenAI. Google’s decision to grant internal engineers access to Claude Opus 5 further signals real-world developer preference. OpenAI’s Codex integrations and GPT-5.6 updates keep it in the lead at 25.6% implied odds for second place, but traders appear to view Anthropic’s specialized coding momentum as more durable through month-end.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · Updated
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