Sullivan & Cromwell has been appointed to act alongside Simpson Thacher Bartlett on the US initial public offering (IPO) of Chinese e-commerce giant Alibaba.

Sullivan has taken a role advising the sponsors on the listing, which Alibaba confirmed last week would take place in the US. The internet giant chose not to list in Hong Kong due to rules in the Asian financial hub which prevent managers from having more voting rights than normal investors.

Media reports say the company is looking to raise more than $15bn in the listing, which would make it among the largest ever initial public offerings.

Legal Week reported in September that Simpson Thacher would be advising the issuer on the deal, replacing magic circle firm Freshfields Bruckhaus Deringer which had originally been instructed to advise Alibaba when the IPO was planned for Hong Kong.

Leading the team at Sullivan is Hong Kong-based US capital markets partner William Chua, though it is understood that the sponsors have not yet been formally appointed.

Simpson Thacher partner Leiming Chen in Hong Kong is leading the advice for Alibaba. Chen is the firm's China practice leader and a senior capital markets partner, and is overseeing a team alongside Palo Alto-based corporate partner Bill Hinman, who advised the underwriters on the IPOs of Facebook and Google.

Alibaba declined to comment.