Will Morgan Stanley Lead Anthropic's IPO? 88% Ahead of S-1

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Morgan Stanley Is the Reported Frontrunner to Lead Anthropic's IPO

Morgan Stanley is reported as the frontrunner for the lead-left role in Anthropic's IPO, alongside Goldman Sachs, JPMorgan and Citi, but no source has confirmed the final allocation. Bloomberg reported on Sept. 4, 2026 that Morgan Stanley is leading the expansion of Anthropic's pre-IPO revolving credit facility to $15 billion. The FT has described the bank as the frontrunner for lead left and said the position was not yet finalised.

Live market odds

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lead Bank in Anthropics Ipo

Each outcome's chance, from what traders are paying right now on Polymarket and Predict.fun.

Morgan StanleyIn this story

93%

PolymarketBest price1.12x89¢Predict.fun1.02x98¢

Goldman Sachs

10%

Polymarket9.09x11¢

JPMorgan: under 1% eachShow all

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On Oct. 21, 2026, Reuters reported that Anthropic could publicly file its S-1 as soon as Friday. On Polymarket, Morgan Stanley's implied probability rose from 82% to 88% over three days, a gain of 6 percentage points, and it stood at 88% on Oct. 21. A public S-1 would turn a role reported by unnamed sources into an underwriting lineup that anyone can read.

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What the S-1 Filing Could Confirm or Reverse for Morgan Stanley

The next checkpoint is the public S-1. Reuters said the filing could come Friday. It did not say the filing is scheduled, and the timeline has already slipped once. In September, Reuters reported that a prospectus expected within a week had been pushed back to late September, and its sources cautioned that timing could change again.

The lead-left bank is the underwriter listed first on the prospectus cover, so the filing will settle the question. If Morgan Stanley appears first, the market's view is confirmed. If Goldman Sachs or another bank appears first, the view reverses. The FT reported that Goldman is expected to act as stabilisation agent. A further delay would keep the question open.

The 6-point rise is a market move, not a confirmed mandate. Traders can follow the Anthropic IPO lead bank market as the filing approaches.

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Until Anthropic files publicly, Morgan Stanley is the strong favorite, not the confirmed lead.