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 With Major Insider Buying 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 Hated Stocks Poised to Pop on Earnings Optimer Pharmaceuticals Optimer Pharmaceuticals ( OPTR) is a biopharmaceutical company focused on discovering, developing and commercializing anti-infective products. This stock is trading up 12% at $12.01 in recent trading. Today's Volume: 2.80 million Average Volume: 608,811 Volume % Change: 679% Shares of OPTR are soaring higher today after the firm said it was exploring a possible sale of the company among a full range of alternatives and replaced its CEO as part of a review of compliance issues. >>4 Biotech Stock Stars Losing Their Luster From a technical perspective, OPTR is gapping sharply higher here right above some near-term support at $10.70 with massive upside volume. This move has briefly pushed OPTR back above its 200-day moving average of $12.61, but it has since then pulled back to around $12. At last check, OPTR has hit an intraday high of $12.74, and volume is well above its three-month average action of 608,811 shares. Traders should now look for long-biased trades in OPTR as long as it's trending above $12 to its 200-day at $12.61 with strong upside volume flows. I would consider any upside volume day that registers near or above its three-month average action of 608,811 shares as bullish. If OPTR can maintain that trend, then this stock will set up to re-test or possibly take out its next major overhead resistance levels at $14 to $15.