According to Investopedia:
It is difficult to identify specific factors that influence the market as a whole. The stock market is a complex, interrelated system of large and small investors making uncoordinated decisions about a huge variety of investments. "The market," so to speak, is not a living entity, rather, it is just shorthand for the collective values of individual companies.
There are basic economic principles that can help explain any up and down market movements and with experience and data, there are more specific indicators that market experts have identified as being significant.
Learn more about this article at Investopedia site : What are the key factors that cause the market to go up and down?
