Anthropic confidentially filed a draft registration statement (Form S-1) with the SEC in June. Traders favor a confirmed IPO before November 1, 2026, at 70%, and leave before October 1 at 27% — the biggest drop on the ladder.
You’re betting on when Anthropic officially confirms an IPO — not when the stock first trades. Each date in the table is its own Yes/No bet — “was the IPO confirmed before this deadline?” — not a single race where only one date wins. So if Anthropic prices the deal on October 15, Before Nov 1, Before Dec 1, and later dates can all pay Yes on that same confirmation; Before Oct 1 pays No.
| Your bet | Chance | Wins if… | $100 bet pays |
|---|---|---|---|
| Before Jan 1, 2027 | 85% | Anthropic confirms an IPO before Jan 1, 2027 | ~$116 |
| Before Dec 1, 2026 | 70% | Anthropic confirms an IPO before Dec 1, 2026 | ~$139 |
| Before Nov 1, 2026 | 70% | Anthropic confirms an IPO before Nov 1, 2026 | ~$139 |
| Before Oct 1, 2026 | 27% | Anthropic confirms an IPO before Oct 1, 2026 | ~$352 |
| Before Sep 1, 2026 | 1% | Anthropic confirms an IPO before Sep 1, 2026 | ~$9,351 |
Other bets on the same path — Before Feb 1 through Before Apr 1, 2027 — already trade near certainty, about 89% to 90%, so they are left out of the table.
Confirmation means the SEC declares the Form S-1 effective, the IPO is priced, or an exchange assigns a ticker — even if trading starts later. Kalshi confirms those milestones from Anthropic and contemporaneous reporting.
The case for Before Nov 1, 2026. Why Before Nov 1 sits at 70%: on June 1, Anthropic said it had confidentially submitted a draft Form S-1 to the SEC for a proposed IPO of common stock, with share count and price still unset and the offering dependent on market conditions. That filing creates the option to go public after review — it does not lock a calendar date. In May, Anthropic closed a $65 billion Series H round at a $965 billion valuation. In mid-July, CNBC and Bloomberg reported that bankers were lining up investor meetings and that a possible window could open as soon as October. An October confirmation clears Before Nov 1 (through October 31) and fails Before Oct 1. That is the 70% case: paperwork is already in, late-stage capital is raised, and the reported October window lands inside the November deadline.
The case for Before Oct 1, 2026. Why Before Oct 1 still sits at 27%: that line needs confirmation by the end of September. The same reported “as soon as October” window sits after that deadline, so media timing that sounds early can still miss Before Oct 1 while clearing Before Nov 1. Before Sep 1 already trades at 1%, so traders have nearly written off an August confirmation. Anthropic’s own June note still left timing to market conditions, with no share count or price set. That is the 27% case: the company would have to finish SEC review and choose to confirm before September ends — earlier than the October window reporters have floated.
Traders put a 70% chance on Anthropic confirming an IPO before November 1 — and about a 30% chance confirmation comes on November 1 or later (or not by then).
Before Sep 1 is already treated as nearly dead at 1%. Before Oct 1 sits at 27%. Before Nov 1 and Before Dec 1 both trade at 70%, and Before Jan 1 rises to 85%. The biggest gap is between October 1 and November 1 — that is where traders disagree most, and it lines up with a reported October window that clears November’s deadline but misses October’s.
At 70% on both Before Nov 1 and Before Dec 1, traders are not adding much extra probability for a confirmation that lands in November but misses December. The disagreement that matches those prices is whether confirmation comes in October — clearing November’s deadline — or slips past October 31.
2 reasons Before Nov 1’s 70% chance can still move:
A public Form S-1, investor meetings ahead of the deal, IPO pricing, or an exchange ticker assignment for Anthropic.