Anthropic's initial public offering has drawn about six times the orders for the shares available, Bloomberg News reported on Thursday, in what could be the largest first-time share sale on record.

Bankers told prospective investors that Anthropic will prioritize its existing backers, leaving some would-be buyers with smaller allocations than expected, the report added, citing people familiar with the matter.

Details of the IPO, including the level of demand, could still change, according to the report. Anthropic could not immediately be reached for comment.

The offering would value the Claude chatbot creator at up to $1.4 trillion, slightly below some investor expectations, setting up a key test of Wall Street's confidence in the artificial intelligence boom.

The AI lab and some of its existing shareholders are aiming to raise up to $64.4 billion in the IPO by selling 825 million shares priced between $70 and $78 each. Shares are expected to start trading on the Nasdaq on November 19 under the symbol "ANT."

Anthropic set the $70-to-$78 price range in an amended filing with the Securities and Exchange Commission earlier this week. Goldman Sachs and Morgan Stanley are leading the offering, with 20 other banks taking part, according to earlier reporting on the deal.

Heavy oversubscription gives Anthropic and its bankers room to price at or above the top of the range, though no decision on pricing has been reported. The debut arrives during a difficult week for AI stocks, making the level of demand a closely watched signal for how much public-market investors will pay for a leading AI developer.