When I was in Shanghai, China, I heard about an anecdote from friends who worked at Shanghai Stock Exchange. In the early July, 1998, Bill Clinton visited Shanghai as a part of his China trip, and one event was to visit the Shanghai Stock Exchange. The original arrangement for him was to ring the opening bell of the market at 9:30 AM on that day, but one Whitehouse aide told Clinton that "according to Wallstreet's calculation, on that day the China stock market would go down". Therefore, Clinton made a slight change on the schedule. Instead of ring the bell, Clinton came to the Exchange in the noon, and gave a 10-minute small speech in the trading hall. In return he got a employee uniform jacket from the Exchange, and he "spent an impressive noon" according to his words. On that day, the market index did go down about 10 points which is about 1%. Are the Wall street guys really so good to be able to calculate the market changes? If they could, what are their methods?