Anthropic's initial public offering has attracted orders for roughly six times the shares available, in what could become the largest IPO, Bloomberg News reported on Thursday.

The developer of the Claude chatbot, together with some existing shareholders, is seeking to raise up to $64.4 billion by selling 825 million shares priced between $70 and $78 apiece. Trading is expected to begin on the Nasdaq on November 19 under the ticker ANT.

At the top of the range, the offering would value Anthropic at up to $1.4 trillion, slightly below what some investors had anticipated. The listing is being watched as a key test of Wall Street's confidence in the artificial intelligence boom.

Citing people familiar with the matter, Bloomberg said bankers have told prospective investors that Anthropic will give priority to its existing backers, meaning some would-be buyers may receive smaller allocations than they had expected.

Bloomberg News cautioned that details of the offering, including the level of demand for the shares, could still change.