Philippine stock market board (Photo credit: Wikipedia)

The American stock market index, as will all such markets around the world, is subject to ups and downs on a daily basis that are caused by numerous factors. For example, who could have predicted the 9/11 terrorists attacks, which had a huge negative impact on world stock markets? When Lehman Brothers, a major American investment bank, collapsed in 2008, the value of all stocks and company shares in the USA fell dramatically. More recently, the Greek debt situation has had an adverse impact not only in Europe but also on the American stock market, as has the political unrest in Syria.