Anthropic's IPO valuation will directly impact the investment return expectations and stock performance of its major backers, Amazon (AMZN) and Google (GOOGL). An extremely high valuation (e.g., >$100B) would benefit these giants and boost sentiment across the AI sector; conversely, a failed IPO or low valuation could dampen confidence in the monetization potential of generative AI. Microsoft (MSFT), as the backer of rival OpenAI, would also be indirectly affected.

April 27, 2026 - April 29, 2026, options including '100–200B', '200–300B', '300–400B', '400–600B', and 'No IPO' all experienced a single-day massive spike of over 30c to near 50c levels on April 28 (e.g., '100–200B' surged from 0.6c to 49.65c), before swiftly retracing to their baselines on April 29. The reason is a severe liquidity shock or a 'fat finger' erroneous market order that instantly cleared the thin order books of these tail-end options. April 5, 2026 - April 7, 2026, the 'No IPO' option price rose from 24.5c to 25.5c, and the '600B+' option surged rapidly from 46.5c to 67.5c between April 3 and April 5, an increase of over 20c. This reflects a dramatic short-term reversal in market sentiment from concerns about IPO delays to renewed extreme optimism for a high-valuation listing. March 22, 2026 - March 25, 2026, the '600B+' option price consolidated at a high level, moving from 82c to 82.5c; the 'No IPO' option gradually fell back to 14c after previously peaking at 19c (March 19), and the '400-600B' option also retreated from its high (10.1c on March 20) to 3.35c. The reason is that previous market concerns about IPO delays or underwhelming valuations dissipated, and capital flowed back into the most optimistic scenario of an ultra-high valuation listing. March 14, 2026 - March 17, 2026, the price of the '600B+' option plummeted from 80.5c to 66c, while '<100B' (rose from 1c to 4.3c) and '400-600B' (rose from 2.8c to 6.85c) saw significant rebounds. The reason is a market correction of the extremely optimistic 'titan IPO' narrative from early March; likely influenced by a macro tech correction or a lack of further positive catalysts, investors have begun hedging tail risks. March 2, 2026 - March 5, 2026, the price of the '600B+' option skyrocketed from ~32c to over 80c, becoming the overwhelmingly dominant outcome. The reason was a sudden shift to an extreme binary consensus, where the market believed Anthropic would either fail to IPO or IPO at over $600B, momentarily discarding the probability of moderate valuation growth.

The implied probability of nearly 87% for a '600B+' valuation on Polymarket diverges heavily from rational expectations of mainstream financial analysts. While the AI sector is booming, a startup achieving an IPO valuation exceeding $600 billion by 2027 remains an extremely low-probability tail event in traditional finance. Market participants appear to have translated emotional call-option premiums or liquidity skew into absolute probabilities, completely ignoring the plausibility of healthy intermediate valuation ranges (e.g., $100-300B).