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 Bargain Stocks to Buy Before 2013 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.RoviRovi ( ROVI) focuses on powering the discovery and enjoyment of digital entertainment by providing a broad set of integrated solutions. This stock is trading up 10.8% at $15.99 in recent trading. Today's Volume: 2.07 million Average Volume: 1.32 million Volume % Change: 172% Shares of ROVI are soaring today after the company reported third-quarter revenue and profit that easily beat consensus estimates and projected higher full-year results as well. From a technical perspective, ROVI is gapping higher up here with monster volume. This move has sent the stock back above its 50-day moving average of $14.77 and above some near-term overhead resistance at $14.70. This action is quickly pushing ROVI within range of triggering another major breakout trade. That trade will hit once ROVI manages to take out some past overhead resistance at $16.91 with high volume. Traders should now look for long-biased trades in ROVI as long as it's trending above its 50-day at $14.77, and then once it sustains a move or close above $16.91 with volume that hits near or above 1.32 million shares. If that breakout triggers soon, then ROVI will set up to retest or possibly take out its next major overhead resistance levels at $18 to $20.