FACTBOX - Key facts about Sri Lanka-born billionaire Rajaratnam

By C. Bryson Hull

COLOMBO (Reuters) - Sri Lankan-born billionaire Raj Rajaratnam's arrest in the largest U.S. hedge fund insider trading case has fuelled a 5 percent drop this week on the Colombo stock market, where he is one of the top investors.

Here are some facts about Rajaratnam, the 52-year-old founder of the Galleon Group hedge fund:

* Born in the Sri Lankan capital Colombo, his father was chairman of Singer Sri Lanka, the local arm of the Singer sewing machine company. He attended St. Thomas' Preparatory School in Colombo, one of the country's most prestigious, and then moved to England to finish his schooling. He studied engineering at the University of Sussex, and earned an MBA from the University of Pennsylvania's Wharton School.

* First gained notice as an analyst for boutique investment banking firm Needham & Co and was named president in 1991. Founded the Galleon Group hedge fund in 1997, which at its peak had more than $7 billion under management. Earned big returns from investments in technology and health care firms.

* Forbes magazine's 2009 list of World Billionaires ranked him the 559th richest person in the world, with an estimated net worth of $1.3 billion. He is believed to be the richest Sri Lankan native in the world at present.

* Married with three children, Rajaratnam lives in New York and is a U.S. citizen. He has made contributions to U.S. President Barack Obama and Secretary of State Hillary Clinton, and backed Sri Lanka's main opposition United National Party. That has led many in the present government to suspect he helped shape some of Washington's criticisms against Sri Lanka's conduct of the final phase of the war against the Liberation Tigers of Tamil Eelam (LTTE) separatists, won by Sri Lanka in May.

* Nonetheless, the government last month accepted Rajaratnam's pledge of $1 million to rehabilitate former LTTE fighters after the end of the 25-year war. Rajaratnam denies allegations his charitable donations found their way to the Tigers. He did give at least $5 million to the Tamil Rehabilitation Organization (TRO) in 2005, to help rebuild after the 2004 tsunami hit Sri Lanka. Two years later, U.S. authorities proved that TRO was funnelling money to the Tigers, which were on a U.S. list of banned terrorist groups. Rajaratnam is Tamil, but his supporters point out that his personal foundation donated millions to help all ethnic communities hit by the tsunami.

* The Central Bank of Sri Lanka this week said its probe into the TRO and Rajaratnam was not finished, and the Sri Lankan Securities and Exchange Commission said it was reviewing his trades on the CSE. He is among the single largest investors in the bourse, personally or through Galleon. Earlier this year, an opposition parliamentarian was charged with violating Sri Lanka's strict foreign exchange controls by transferring $3 million on Rajaratnam's behalf into the stock market. The politician, Ravi Karunanayake, is a strident critic of President Mahinda Rajapaksa and calls the charges politically motivated and baseless.

(Editing by Ron Popeski)