Billionaire financier George Soros invested last year in Alibaba.com,  becoming the third-largest shareholder in the operator of China's largest e-commerce site, Alibaba's chief executive says.

Soros invested in Alibaba in the third quarter of 2009, chief executive David Wei told investors at the company's recent annual general meeting in the Chinese city of Shenzhen, just across the border from Hong Kong.

He did not specify the size of Soros' investment, or whether Soros was the third-largest investor overall, or third-largest among non-insiders, said Alibaba spokesman John Spelich, who was at the meeting.

The company's largest shareholder is Alibaba Group with a 73 percent stake, followed by a Morgan Stanley affiliate with 1.5 percent, according to Reuters data. All other shareholders hold 0.36 percent or less of the company's stock.

Alibaba shares rose 5.3 percent on Friday in Hong Kong, outpacing a 1.4 percent drop for the Hang Seng Index.

On Thursday after market close, the company, whose parent Alibaba Group is 40 percent owned by Yahoo, reported its best results in a year on strong paid-customer growth.