WINDERMERE, Fla. ( Stockpickr) -- Professional traders who run mutual funds and hedge funds don't just look at a stock's price moves; they also track big changes in volume activity. Many times when above average volume moves into equity it precedes a large spike in volatility. Major moves in volume can signal unusual activity, such as insider buying or selling -- or buying or selling by "superinvestors.">>5 Bigt Stocks to Trade for Gains Unusual volume can also be a major signal that hedge funds and momentum traders are piling into a stock ahead of a catalyst. These types of traders like to get in well before a large spike, so it's always a smart move to monitor unusual volume. That said, remember to combine trend and price action with unusual volume. Put them all together to help you decipher the next big trend for any stock. Let's take a look at a several stocks rising on unusual volume today. They are all recording volume in midday trading that is already at least 50% above their average trading volume for a full day.