Xiao Jianhua, the Chinese Canadian billionaire and onetime trusted financier to China's ruling elite, was sentenced to 13 years in prison and his company fined $8 billion after he pleaded guilty to bribery and other crimes.

The Tomorrow Group umbrella of companies was once worth hundreds of billions of dollars and was fined $1 million.

Mr. Xiao was taken from his home in Hong Kong and taken to China, where he was held incommunicado. When Chinese officials confirmed he was on the mainland, there was no news of him. The charges against him were kept a secret last month as he stood trial.

The trial was attended by top Chinese officials, including the deputy to the National People's Congress and members of the China People's Political Consultative Conference. Mr. Xiao and his business relationships were once an example of the close ties between China's business world and the political elite.

The demise of the Tomorrow Group in 2020 was a sign that an era of freewheeling finance, in which wealthy executives used their political connections to build huge companies that scoop up trophy assets at home and abroad, was over.

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The court said on Friday that Mr. Xiao had been convicted of a number of charges, including illegally absorbing public funds, betraying the use of entrusted property, and illegally using funds and bribes. Mr. Xiao admitted guilt and cooperated with the recovery of stolen funds.

The Tomorrow Group did not respond to a request for comment. Requests for comment from the Canadian Embassy in Beijing were not responded to. The embassy had submitted several requests to attend the trial of Mr. Xiao, who is a Canadian citizen.

Mr. Xiao used Tomorrow Group to build financial ties with companies in all areas of China's economy, from banking and insurance to rare metals, coal and real estate. It had financial stakes in some of the biggest firms in China.

Mr. Xiao had a net worth of $5.8 billion. The country's financial stability was threatened by tomorrow group.

It had a stake in the bank. The bank extended loans to other Tomorrow Group companies but kept them off the books for a long time. Regulators took over the bank after it was pushed to the verge of insolvency.

Regulators dismantled Tomorrow Group in order to send a strong message to China's corporate sector to rein in excessive borrowing.

According to the court, Mr. Xiao and Tomorrow Group bribed government officials with shares, real estate holdings and other assets worth $100 million.

The criminal acts of Tomorrow Groups and Xiao Jianhua seriously damaged the financial management order, jeopardized the national financial security, and should be severely punished according to law.

The man who took charge of China in 2012 was determined to rid the country of corruption.

The two had a previous contact. According to a New York Times investigation, Mr. Xiao bought shares in an investment company owned by the sister of a man. A spokeswoman for Mr. Xiao said that the couple did it for the family.

Wang gave reporting.