Investing is by definition a long term activity. If you're interested in the short term movements of the stock market, you're just speculating. In the long term, the stock market will be more profitable than putting your money in the bank. If this wasn't the case, companies will go bankrupt, as their activites will be less profitable than their financing costs.

Obviously, few people expect a stock market boom these days, so if you're putting your money there, you should possess good information about the companies you are investing in, or be in it for the long term.