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.>>5 Dividend Stocks Itching to Pay You More Major moves in volume can signal unusual activity, such as insider buying or selling -- or buying or selling by "superinvestors." 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 Breakout Stock Plays: Must-See Charts Sarepta Therapeutics ( SRPT) This company is focused on developing RNA-based therapeutics to improve and save the lives of people affected by serious and life-threatening rare and infectious diseases. This stock is trading up 7.4% at $28.98 in recent trading. Today's Volume: 2.44 million Average Volume: 2.57 million Volume % Change: 53% Shares of SRPT are ripping higher today after Piper Jaffray said the stock has the potential to be a $160 stock with a $4 billion market cap, but its nearer-term range could be $60 to $80. From a technical perspective, SRPT is bouncing up here with decent volume and the stock is challenging some near-term breakout levels at $27.94 to $29.19. At last check, shares of SRPT have hit an intraday high of $29.48 and volume is just a bit under its three-month average action of 2.57 million shares. Traders should now look for long-biased trades in SRPT as long as it's trending above its recent breakout level of $27.94 with strong upside volume flows. I would consider any upside volume day that registers near or above its three-month average volume of 2.57 million as bullish. If SRPT can maintain that trend, and especially hold a trend above its next breakout levels at $29.19 to $29.48, then this stock will set up to re-test or possibly take out its next major overhead resistance levels at $32.50 to $35.