'The time to invest,' Nathan Rothschild is supposed to have said, 'is when there is blood on the streets.' Thankfully the streets of Bangkok remain blood-free following Tuesday night's coup. But considering the renowned banker lived in a far more sanguinary age, perhaps we should update his advice to read: 'The time to invest is when there are tanks on the streets,' and ask whether we should take this opportunity to buy shares in Thailand. At first glance the signs do not look good. The Thai stock exchange was closed yesterday after the country's new military masters decreed a public holiday. But Thai stocks listed abroad and the shares of foreign companies with sizable assets in Thailand, took a beating. Shares in Thai Beverage, the company responsible for Black Cat rice whiskey and other similarly potent brews, plunged 7 per cent in early Singapore trading. Hutchison Telecommunications International and Singapore Telecom, both of which own businesses in Thailand, fell, as did the shares of Japanese carmakers with factories in the country. The stocks of some Southeast Asian airlines followed suit. Meanwhile, both Fitch and Standard & Poor's put the credit ratings of a clutch of Thailand's leading banks and corporations on their watch lists for possible downgrades. On foreign exchange markets, the baht slumped. When the domestic financial markets reopen, supposedly today, observers expect jittery fund managers will pull money out of the country, driving the local stock market and the currency sharply lower. For some investors at least, the predicted sell-off could provide a buying opportunity. For example, Goldman Sachs economist Adam Le Mesurier issued a research note yesterday predicting the coup could turn out to be mildly bullish for equities on the grounds that it could help clear the political air after months of uncertainty. There are reasons to think he might be right. For one thing, yesterday's sell-off, although initially steep, proved short-lived. Thai Beverage recovered from its early plunge to finish just 2 per cent down on the day which is roughly where both HTIL and SingTel ended up. And the baht soon stabilised after falling nearly 2 per cent on Tuesday. That is peanuts compared with daily swings of 5 per cent or more during the 1997 Asian crisis and the currency remains up 9 per cent so far this year. Even more encouraging, there were few signs that dealers were selling down other regional markets as proxies for Thai assets, indicating there is little chance of contagion spreading through Southeast Asia. History, too, gives cause for hope. The last time armed soldiers took control of the streets of Bangkok was in the infamous Black May of 1992. There was a sharp sell-off at first but as events paved the way for a peaceful general election the following year, Thailand's stock market entered a protracted rally that saw local stocks climb 150 per cent over the next 18 months. Similarly, in Indonesia, the 1998 ousting of Suharto as president led to an initial period of stock market volatility, followed by a doubling of prices as the republic moved towards its first free presidential election the next year. In the Philippines, recent coup attempts have also been good for local stock prices, preceding bull runs both in 2003 and earlier this year. Even so, following Mr Rothschild's advice and buying into Thai stocks in expectation of a post-coup relief rally will take steady nerves and a strong stomach. Then again, so does Black Cat.