Du Jun, convicted yesterday in Hong Kong's biggest insider trading case, was once a rising young investment banker in the city because of his strong mainland background, western education and deep knowledge of bond trading. Little is known about his background and family other than that he was born in Beijing, attended Columbia University in the United States and worked in New York for some years. In 1996, he came to Hong Kong to work at Merrill Lynch as a bond trader. One investment banker who worked with Du said he was smart and a good trader but had a quick temper. Du rarely joined social gatherings and kept a low profile, his former colleague said. The mainland economy was growing rapidly and many firms were engaged in mergers and acquisitions or sought initial public offerings. International investment banks were eager to hire mainlanders who had a western education and could speak fluent English. Du joined Morgan Stanley Asia in 2001 and rose to become managing director of the fixed-income department a few years later at 35. Court documents showed he earned a base salary of HK$1.45 million a year plus bonus, which stood at US$2.3 million in 2006. This means he had total annual income of HK$19.39 million or HK$1.62 million per month in 2006 - the year before his HK$87 million worth of illegal trades based on inside information. Regulatory sources said the highly paid banker had few assets in Hong Kong and only rented a flat where he lived with his wife. He was arrested when he returned to Hong Kong from the mainland to collect a painting and an air purifier. During his 38-day trial, few friends or relatives showed up in court other than his wife, Li Xin. The former banker, who had been on bail, is now in custody awaiting sentencing.