A stock's float is the number of issued shares available for public trading. Because momentum depends on supply and demand, the size of a stock's float can affect its potential for volatility. Stocks with relatively few outstanding shares can fairly easily encounter situations where demand far exceeds supply, thus creating a lot of momentum. For example, when a stock with only 8 million shares outstanding suddenly becomes popular, it can zoom up in price much faster than a stock with 800 million shares outstanding.