SHANGHAI - Alibaba co-founder Jack Ma has penned a rare lengthy memo to employees that expresses support for the internet giant's restructuring efforts, a sign that he may be willing to take a more active role after spending the last few years out of the spotlight.

Alibaba's Hong Kong-listed shares surged 5% in morning trade 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.

The post was the longest made by Ma on Alibaba's intranet in five years.

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)