Anthropic flips to 81% favorite over OpenAI on Polymarket IPO contract after May lead collapses
Anthropic has surged to an 81% favorite over OpenAI on Polymarket's head-to-head IPO contract, a dramatic reversal from late May when OpenAI led at 75% and Anthropic languished at 25%. The repricing follows Anthropic's filing of IPO paperwork, which intensified the race between the two AI labs to go public. On a separate Polymarket contract, traders slashed Anthropic's odds of listing before September 30 to 30% on June 3, down 37% in a single day, showing sharp disagreement even within the same platform on timeline questions. Kalshi also offers contracts on which company debuts first, though no price levels from that venue appear in the available source material. The volatility marks the first major sentiment shift in AI IPO prediction markets since both platforms launched competing AI valuation contracts.
Traders now face a 59-point arbitrage gap between venues on the same AI exit outcomes, forcing arbitrageurs to choose which platform's data partnership or retail flow better captures actual IPO pipeline timing. The swing tests whether Polymarket's crypto-native trader base overreacts to filing headlines versus Kalshi's institutional-sourced pricing.
The flip echoes the persistent 59-point spread between Kalshi and Polymarket on OpenAI IPO odds, showing how AI-exit sentiment can invert within weeks across venues with different data feeds and trader bases.