WINDERMERE, Fla. ( Stockpickr) -- Professional traders running mutual funds and hedge funds don't just look at a stock's price moves; they also track big changes in volume activity. Often when above-average volume moves into an 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 Stocks Ready to Break Out 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. With that in mind, let's take a look at several stocks rising on unusual volume today. >>5 Stocks Set to Soar on Bullish Earnings Clean Energy Fuels Clean Energy Fuels ( CLNE) is engaged in the business of selling natural gas fueling solutions to its customers mainly in the U.S. and Canada. This stock is trading up 4.4% at $13.92 in recent trading. Today's Volume: 1.43 million Average Volume: 1.16 million Volume % Change: 98% Shares of CLNE are ripping higher here after Ascendiant Capital initiated the stock with a buy rating and a $15.50 price target. From a technical perspective, CLNE is trending higher here right off its 200-day moving average of $13.38 with above-average volume. This move has pushed shares of CLNE into breakout territory, since the stock has taken out some near-term overhead resistance at $13.62. Shares of CLNE are now quickly moving within range of triggering another major breakout trade. That trade will hit if CLNE manages to take out some key overhead resistance levels at $14.37 to $14.69 with high volume. Traders should now look for long-biased trades in CLNE as long as it's trending above its 200-day at $13.38 or above $13.62, and then once it sustains a move or close above those breakout levels with high volume that hits near or above 1.16 million shares. If that breakout triggers soon, then CLNE will set up to re-test or possibly take out its next major overhead resistance level at $16.75.