Anthropic is due to trade under the symbol ANT. It has been described as listing on 19 November and as the first fully AI-focused company to go public, making the debut a test of the technology's commercial future. The company has also been reported as floating this month, while the listing has separately been described as now expected early next year.
The loss-making company said it would offer shares at between $70 and $78 each, below what had been expected, and raise up to $64 billion in the flotation.
At about $1.3 trillion, the possible valuation would sit below that of SpaceX, Elon Musk's rocket, satellite and artificial intelligence company. SpaceX listed in June and was valued at nearly $1.8 trillion.
In results for the six months to the end of June, Anthropic's revenue jumped to $16.2 billion from $1.1 billion in the same period a year earlier.
The scale of the proposed valuation comes despite a warning the company issued last month that AI could pose catastrophic or existential risks to humanity.
Anthropic said advanced AI systems"could, if not developed, deployed, and operated with appropriate safeguards, oversight, and security measures, pose catastrophic or existential risks to humanity, particularly if such systems were misused, replicated, weaponised, or allowed to operate with a high degree of autonomy".
The share sale will show whether public investors will back a pure AI business that is still losing money, even as its revenue has surged and as the company itself flags the dangers of powerful systems.
How the stock is received will be watched as a measure of demand for AI, and of how far that demand stretches when a leading developer is also warning of catastrophic harm.