do no greater damage. After the previous coup, in February 1991, the SET Index tumbled 7.3% on the first day of trading before rallying 24% in the next two months. About six stocks fell for every one that rose at the exchange, with 43 billion baht ($1.1 billion) changing hands. That was the most since 51 billion baht in shares traded on April 5, the day after Thaksin said he would step down to end a political crisis. The SET rose 3.1 percent that day. "The initial reaction was kind of a knee-jerk reaction," said Adithep Vanabriksha, who helps manage $1.6 billion at Aberdeen Asset Management Co. in Bangkok. "Coups aren't viewed positively in the first instance, at least. Still, we wouldn't recommend investors sell. Valuations are still quite cheap." Shin Corporation, which owns Thailand's largest mobile-phone operator, fell 1.75 baht, or 5.7 percent, to 29.25. Thaksin's family sold its stake in the company to a group of investors led by Singapore's state-run Temasek Holdings Pte. The family didn't pay tax on the $1.9 billion deal, sparking protests and a political crisis that culminated in this week's coup. Shin's Advanced Info Service Pcl unit, which is the country's biggest mobile-phone operator, lost 2.50 baht, or 2.7 percent, to 90.50. Shin Satellite Pcl, the country's only satellite operator, plunged 1.20 baht, or 13 percent, to 7.85. ITV Pcl, a television network operator controlled by Shin, tumbled 0.46 baht, or 13 percent, to 2.98. "It's a knee-jerk reaction," said Patipat Pattaphongse, director of research at KGI Securities (Thailand) Pcl in Bangkok. "People still tend to affiliate Thaksin with Shin but he's out of the loop. The sell-off is a little misguided." PTT Pcl, the country's biggest publicly traded company and its largest energy provider, fell 6 baht, or 2.8 percent, to 212. PTT Exploration & Production Pcl, the second-biggest listed company and its largest explorer, dropped 2 baht, or 1.9 percent, to 105. The two stocks accounted for 33 percent of the SET's decline. Siam Cement Pcl, the country's biggest cement and petrochemical company, rose 2 baht, or 0.8 percent, to 244, after losing up to 2.5 percent in early trading.Bangkok Bank Pcl, the No. 1 lender by assets, added 1 baht, or 0.9 percent, to 114, after falling as much 2.7 percent. Banks as a group gained 0.8 percent, one of two industry indexes advancing within the SET. Elsewhere Italian-Thai Development