By Casey Hall

SHANGHAI (Reuters) -Alibaba co-founder Jack Ma has penned a lengthy memo to employees that expresses support for the internet giant's restructuring efforts, a rare move from the billionaire after spending the last few years out of the spotlight.

Alibaba's Hong Kong-listed shares surged 5% after the post.

The post, made in an internal company forum, comes one year after Alibaba announced its decision to split into six units - the biggest shake-up in its 25-year history.

It has had a tumultuous time since then, installing a new CEO, announcing and then abandoning the listings of its cloud and logistics units. At the same time, it has lost ground in e-commerce to low-cost rivals such as PDD Holdings and ByteDance-owned Douyin, the Chinese version of TikTok.

In the post, which was roughly a page long, Ma praised the leadership of CEO Eddie Wu and Chairman Joe Tsai and said the split into six divisions had helped streamline decision-making, making Alibaba more agile and customer-focused.

He also said Alibaba had made many mistakes in the past.

"We must not only have the courage to admit and correct yesterday's problems in a timely manner but also make reforms for the future," he said, according to a copy of the post seen by Reuters and verified by a source who had viewed it on Alibaba's intranet.

"This year, amid the many doubts and pressures on the company internally and externally, I saw the birth of a strong and brave Alibaba team," he added.

The post was the longest made by Ma, who owns roughly 4% of Alibaba, on the company's intranet in five years. Alibaba did not immediately respond to a request for comment on the post.

Jacob Cooke, CEO of e-commerce consultancy WPIC Marketing + Technologies, said he believed the letter was aimed at "restoring internal and external confidence in Alibaba's leadership" given that "the chorus of negative voices seems to have risen in 2024."

Alibaba's shares have declined 27% in the past 12 months, giving it a market capitalisation of some $178 billion. Rival PDD, which briefly overtook Alibaba in terms of market value last December, is not far behind with $160 billion.

Ma, China's best-known tech entrepreneur, publicly criticised Chinese regulators in a speech in October 2020, derailing a massive listing by fintech company Ant Group, which he also founded. That was followed by regulatory crackdowns on the Chinese tech sector, including a fine of $2.8 billion for Alibaba, with Ma largely withdrawing from public life.

Ma spends much of his time abroad, especially in Japan where he is a visiting professor at Tokyo College, a research institute run by the University of Tokyo.

(Reporting by Casey Hall; Editing by Edwina Gibbs)