HONG KONG (Reuters) - China’s biggest e-commerce company Alibaba Group Holding Ltd has filed confidentially for a Hong Kong listing that could raise up to $20 billion as early as the third quarter of this year, a person with direct knowledge of the matter said.

A deal of that size would be the biggest follow-on share sale globally in seven years and give Alibaba funds for technology investment - a priority for China as economic growth slows and a trade spat with the United States intensifies.

Alibaba holds the record for the world’s largest initial public offering with its $25 billion float in New York five years ago.

Then, the company had initially hoped to float in Hong Kong but the tech firm’s management structure clashed with the city’s listing rules. Hong Kong Exchanges & Clearing, the city’s bourse operator, changed its listing rules last year - primarily with the aim of attracting Chinese tech groups.

Alibaba declined to comment on the deal when contacted by Reuters. Japan’s SoftBank Group, which is Alibaba’s largest shareholder with a 28.7% stake, did not immediately respond to a request for comment.

The person with knowledge of the matter was not authorized to speak with media and so declined to be identified. News of the filing was first reported by Bloomberg.

Investment banks China International Capital Corp Ltd and Credit Suisse Group AG are leading the deal. Both banks declined to comment. No other banks have been formally mandated as yet.

BIG DEAL FOR HONG KONG

A listing by Alibaba in Hong Kong will be seen as a victory for the city by its stock-focused market professionals, who mourned the lost trading revenue when the e-commerce group chose to float in New York.

Trading in Alibaba shares averaged $2.2 billion a day in the first quarter of this year, according to Refinitiv data, compared with average daily turnover on the Hong Kong exchange of $12.9 billion in the same period.

Listing in Hong Kong would also give mainland Chinese investors their first direct access to one of their country’s biggest success stories, via the stock connect trading link between Hong Kong, Shanghai and Shenzhen.

Since its U.S. listing, Alibaba’s market value has nearly doubled and is now $423 billion, the largest in Asia-Pacific.

The filing comes amid growing political unrest in Hong Kong this week that raised concerns over the potential impact on the city’s financial market and businesses.

Thousands of protesters have taken to the streets in the southern Chinese territory this week over a planned extradition agreement with mainland China.

Logistics real estate developer ESR Cayman Ltd on Thursday pulled what would have been the largest Hong Kong listing so far this year, citing “current market conditions”.

So far this year, the benchmark Hang Seng index has gained 5.6% compared with a 22.4% jump in China’s blue-chip CSI 300 and a 14.9% rise in the U.S. S&P 500.