HONG KONG: Goldman Sachs has joined the growing list of investment banks working on Chinese financial technology firm Ant Group's mammoth initial public offering of up to $30 billion, two people with direct knowledge of the matter said.

Ant, backed by Chinese e-commerce giant Alibaba Group, plans to list simultaneously in Hong Kong and Shanghai, in what sources have said could be the world's largest IPO and come as soon as October.

Wall Street major Goldman Sachs has been hired as a joint lead manager on the Hong Kong leg of the IPO, said the people, who declined to be named as they were not authorised to speak to the media on this subject. A spokesman for Goldman Sachs, which also acted as a joint lead manager on Alibaba's $12.9 billion secondary listing in Hong Kong last year, declined to comment.

The IPO of Ant, already the world's most valuable unicorn - or billion-dollar unlisted tech firm - would be the first simultaneous listing in Hong Kong and Shanghai's year-old STAR Market.

The Hong Kong leg of the IPO is being sponsored by China International Capital Corp (CICC), Citigroup, JPMorgan, and Morgan Stanley. Credit Suisse is working as a joint global co-ordinator.

The top-ranked banks in a Hong Kong IPO are known as sponsors and carry legal liability for the accuracy of the prospectus. Under them are joint global coordinators, and on the bottom rung are joint lead managers.