Anthropic has tapped law firm Wilson Sonsini to begin work on one of the largest initial public offerings ever, which could come as soon as 2026, as the artificial intelligence start-up races OpenAI to the public market.

The maker of the Claude chatbot, which is in talks for a private funding round that would value it at more than $300bn, has chosen the US west coast law firm in recent days, according to two people with knowledge of the decision.

The start-up, led by chief executive Dario Amodei, has also discussed a potential IPO with big investment banks, according to multiple people with knowledge of those talks. The people characterised the discussions as preliminary and informal, suggesting that the company is not close to picking its IPO underwriters.