The court said Thaksin had concealed his ownership of shares in his family telecommunications conglomerate Shin Corp. during his five years in office and geared government policies to benefit the company, but ruled that $900 million amassed before his premiership be unfrozen.
Authorities said major violence was unlikely in response to the ruling but mobilized thousands of police and troops to pre-empt any backlash by supporters of the 60-year-old fugitive at the center of a five-year political crisis in Southeast Asia's second-biggest economy.
Prior to the ruling, analysts said any decision allowing Thaksin's family to keep a portion of the assets would be more favorable for markets in the short term by reducing the risk of an imminent showdown in Thailand's divisive color-coded crisis.
"The partial seizure of the assets should be what financial markets prefer because both sides can claim victory," said Prapas Tonpibulsak, chief investment officer at Ayudhya Fund Management.
The judges said Thaksin had abused his power in all five major cases against him, which included shaping telecoms and satellite policies, including concessions fees and state loans, to benefit Shin Corp.
Thaksin, ousted in a 2006 coup and convicted in absentia of graft, has denied the charges from self-imposed exile in Dubai.
After the verdict, he said he was not surprised. "The Thai law is like an assumption. It severely fails to meet international standards," he said in a video-link to about 800 supporters who gathered to rally behind him.
Some of his red-shirted supporters cried or sobbed quietly, while others shouted in frustration and anger.
Some analysts say a court verdict unfavorable to Thaksin, could have added weight to allegations he was the victim of a political vendetta and spark an angry response from supporters.
Although the verdict has turned a new page in an intractable political crisis that has alarmed many investors, few believe it will provide any hope of a long-term resolution.
The final verdict was reached after more than seven hours and came after the close of Thailand's stock market, which reopens on Tuesday after a long weekend holiday, allowing investors to weigh up the outcome.
Security remained tight around Bangkok's Supreme Court on what has become known as "Judgment Day,” with cell phone signals jammed to prevent remote-detonated bombings and judges ferried to the courthouse, some from safe houses, in bullet-proof cars.
Six hundred police guarded the court. Security agencies said thousands of riot troops were on standby in case of unrest.
The pro-Thaksin "red shirt" movement, whose demonstrations last year sparked Thailand's worst street violence in 17 years, plans a mass rally in Bangkok on March 14 but said it would not protest on Friday, whatever the verdict.
The twice-elected Thaksin has said he will fight any seizure of the assets from exile. He is believed to be in Dubai.
