Thai authorities have launched an investigation into alleged insider trading relating to Singapore’s Temasek Holding’s USD1.9 billion takeover of Shin Corp, the conglomerate founded by Thaksin Shinawatra, the Thai prime minister. On Monday the Shinawatra family sold its 49.9% stake in Shin Corp to Temasek. For several weeks before the long-rumoured sale, Shin Corp’s management and the Shinawatras denied any knowledge of a takeover bid, even as talk of a deal sent Shin Corp’s share price up by 25%. A Bangkok-based merger and acquisition expert quoted by the Financial Times said: ‘It is just incredible that the largest deal in the history of the country can go on without an announcement. It’s a very poor comment on corporate governance.’ Lawyers advising the parties, and the Thai stock market authorities, said the Shinawatras, as owners of listed shares, had no legal obligation to disclose their intentions to sell before completing the transaction.