The biggest single controlling factor in the stock market remains the supply and demand created by the average trader, as stated by Investopedia. From the smallest retail trader to the best hedge fund managers, each individual trader contributes to the volatility and equity that is the market.
The stock market is also sometimes referred to as the equity market, explains Investopedia. This need for equities to trade is met by market makers who compose the markets, which answer to the exchanges. In 2015, trading is completed electronically via high-speed data cables that allow anyone to open a trading account and execute trades on the financial market of their choice using the instrument of their choice.
The biggest driving factor behind the average trader is emotion, states Investopedia. Fear and greed comprise the largest controller emotions that create the market's volatility, allowing other traders to capitalize on the movements of the price action. Above the traders, market makers and trade exchanges is the Security and Exchange Commission, the government-controlled entity responsible for overseeing the markets. The Security and Exchange Commission investigates any fraud and has the power to halt a stock any time without notice, which often has a significant influence on it's price.