Google overtakes Anthropic in near-term AI model market as midterms volume surges

Anthropic's lead in the end-of-October AI market collapsed after Google released Gemini 4 Argon. Political markets in the US and Brazil drew heavy volume ahead of their elections.

Democratic sweep odds hold firm as Senate data sharpens

The Democrats Sweep outcome held at 63.0% even as the split-control scenario — Republican Senate, Democratic House — nudged up 1.7 points to 29.5%, drawing $931,045 in large trades over seven days. The move tracks fresh polling: Nate Silver's generic-ballot tracker hit D +9.0 as of October 2, a cycle high, while Fox News surveys show Democrats leading in Texas, Iowa, and Michigan Senate races. Volume on Kalshi and Polymarket combined exceeded $43 million, reflecting genuine uncertainty about whether Democrats can flip the Senate alongside an increasingly comfortable House path.

Outcome	7 days ago	Now	Change
R Senate, D House	27.8%	29.5%	+1.7 pts

24h volume $2,765,906 · 3 platforms · 32 large trades totalling $931,045 (7d).

Compare live odds for 2026 Midterms: Congress Balance of Power? — For Feb 2027

Brazil first-round vote drives volume spike to $3 million

With Brazilians heading to the polls on October 4 for the first round, 24-hour volume jumped to $3,122,789 — a 455% weekly increase — even as Flávio Bolsonaro's consensus probability slipped a modest 0.6 points to 56.8%. Final-week polling showed Bolsonaro and Lula statistically tied in runoff simulations, with Datafolha putting the second round at 47–45 for Lula; markets price Bolsonaro as the narrow favourite heading into what is almost certainly an October 25 runoff. The 3.5-point cross-platform spread on Lula's odds between Polymarket and other venues is the widest gap in the market.

Outcome	7 days ago	Now	Change
Flávio Bolsonaro	57.4%	56.8%	-0.6 pts

24h volume $3,122,789 · 4 platforms · 35 large trades totalling $509,716 (7d).

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Google surges to favourite after Gemini 4 Argon launch

Anthropic collapsed 52.3 points to 36.3% while Google rose to 58.2% as the consensus end-of-October favourite, the sharpest single-week swing in this shortlist. The move followed Google's launch of Gemini 4 Argon on September 30. A 7.4-point spread between Polymarket US and Polymarket on the Google outcome reflects how quickly traders on different platforms repriced the news.

Outcome	7 days ago	Now	Change
Anthropic	88.5%	36.3%	-52.2 pts

24h volume $237,344 · 2 platforms · 17 large trades totalling $72,504 (7d).

Compare live odds for Which company has the best AI model end of October?

Google's year-end AI odds jump 26.7 points in a week

Google's probability for having the best AI model at year-end surged 26.7 points to 36.8%, though Anthropic retained its lead at 52.0%. The move mirrors the end-of-October market reaction to Gemini 4 Argon's launch, with traders reassessing Google's longer-horizon competitiveness. A notable 5.2-point spread on xAI between Polymarket and Polymarket US suggests lingering disagreement about where that company lands by December 31.

Outcome	7 days ago	Now	Change
Google	10.0%	36.8%	+26.7 pts

24h volume $46,972 · 2 platforms · 9 large trades totalling $20,668 (7d).

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The takeaway

Two AI markets and two political markets dominated volume this window, with Google's model launch moving hundreds of thousands of dollars in a single week. Attention and capital are concentrating on events with binary, near-term resolution — Brazil's runoff and the November midterms — while the AI races remain the most volatile markets by probability swing.

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Corrected on 7 October 2026: we removed sections that misreported game results or price moves, and fixed other errors of fact.