HONG KONG (NYTIMES) - China's economy is on a tear. Factories are humming and foreign investment is flowing in. Even so, the wealthy and powerful people atop some of the country's most prominent companies are heading for the exits.

The latest are Mr Pan Shiyi and Ms Zhang Xin, the husband-and-wife team that runs Soho China, a property developer known for its blobby, futuristic office buildings.

In striking a deal this week to sell a controlling stake to investment giant Blackstone for as much as US$3 billion (S$4.03 billion), Mr Pan and Ms Zhang are turning over the company as high-profile entrepreneurs come under public and official scrutiny in China like never before.

Soho China did not respond to a request for comment.

China's most famous tycoon, Alibaba co-founder Jack Ma, has kept an uncharacteristically low profile since late last year, when the government began a regulatory crackdown on his companies and the wider Internet industry.

Mr Colin Huang, founder of Alibaba rival Pinduoduo, resigned as chairman in March, less than a year after he stepped down as CEO. In May, Mr Zhang Yiming, founder of TikTok's parent company, ByteDance, said he would hand over the CEO post to focus on long-term strategy.

Under the Communist Party's top leader Xi Jinping, nationalism has been resurgent in China, and the government has sought to exert more direct influence over the private sector.

Even before this week's sale, Mr Pan and Ms Zhang had been avoiding the spotlight more than they did during an earlier, freer era of China's economic revival.

"For big tycoons in China, nowadays they need to be careful in general," said Assistant Professor Ling Chen, who studies state-business relations in China at the School of Advanced International Studies at Johns Hopkins University.

Highly visible entrepreneurs, particularly those in risky sectors such as real estate and finance, know that regulators will scrutinise their businesses more closely someday, Asst Prof Chen said. "They just don't know when that day is."

The rise of Mr Pan and Ms Zhang, as they have described it in media interviews and online, mirrored China's rise.

Mr Pan, 57, grew up poor in the remote north-western province of Gansu and briefly worked at a state-owned oil company after college. In the early 1990s, he started a real estate company in the southern province of Hainan with a few friends and made his first bucket of gold.

Ms Zhang, 55, was born in Beijing and immigrated to Hong Kong at age 14. She worked in factories for years before going to Britain with the equivalent of a few thousand dollars in savings. After receiving a master's degree in economics at Cambridge, she worked at Goldman Sachs.

She was introduced to Mr Pan in 1994. He proposed four days later. In 1995, they founded the company that would later be renamed Soho China.

As their towers began piercing the Beijing and Shanghai skylines, Ms Zhang and Mr Pan became an "it" couple in business and society circles. Top entrepreneurs, government officials and intellectuals attended their parties.

Mr Pan was also one of the first Chinese business leaders to recognise the power of the Internet in marketing and public relations. He wrote a popular blog in the 2000s. Then, when Weibo, a Twitter-like social media platform, came along, he quickly became one of its most influential voices, amassing more than 20 million followers.

In his Weibo posts, he wrote about his childhood, China's real-estate policies and air pollution in Beijing. He was never too pointed in expressing his opinions. But he wanted China to learn from its mistakes, such as its cruel treatment of the moneyed and educated classes during the Cultural Revolution.

After Mr Xi took office as China's top leader in 2013, the authorities began going after business people and intellectuals with big online followings. The police that year arrested Wang Gongquan, a friend of Mr Pan's and supporter of human rights causes, on charges of disrupting public order.

Mr Pan and Ms Zhang began selling off property holdings in China and spending more time in the United States. The Zhang family and the Safra family of Brazil, long involved in international banking, teamed up to buy a 40 per cent stake in the General Motors building in the New York City borough of Manhattan.

Chinese news outlets asked why Soho China was letting go of billions of dollars in assets in China. They noted that the couple donated generously to Harvard and Yale but not to Chinese universities.

After media reports accused Soho China of "fleeing" Shanghai by selling projects there, Mr Pan wrote on Weibo: "Buying and selling is normal. Don't read too much into it."

The company's last big public event was the opening of Leeza Soho, a lithe, spiraling skyscraper in Beijing, in late 2019. Famed architect Zaha Hadid, who designed the tower and who is a friend of Ms Zhang, had died a few years earlier.

On Wednesday night (June 16), minutes after Soho China announced the sale on its official Weibo account, Mr Pan reposted the announcement without comment, in what online commentators called a "silent farewell."