DELAFIELD, Wis. ( 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 Stocks Setting Up to Break Out 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. >>5 Big Trades for a September Bounce With that in mind, let's take a look at several stocks rising on unusual volume today. Mercadolibre Mercadolibre ( MELI) operates an online trading site for the Latin American markets. This stock closed up 7.1% at $128.50 in Monday's trading session. Monday's Volume: 814,000
Three-Month Average Volume: 479,008
Volume % Change: 69% >>5 Rocket Stocks to Buy This Week From a technical perspective, MELI ripped higher here right above its 50-day moving average of $117.07 with above-average volume. This move pushed shares of MELI into breakout territory, since the stock took out some near-term overhead resistance at $125.30. Shares of MELI are now quickly moving within range of triggering another big breakout trade. That trade will hit if MELI manages to take out some more near-term overhead resistance at $130.74 with high volume. Traders should now look for long-biased trades in MELI as long as it's trending above $125 or $124 and then once it sustains a move or close above $130.74 with volume that's near or above 479,008 shares. If that breakout triggers soon, then MELI will set up to re-test or possibly take out its 52-week high at $136.52. Vipshop Vipshop ( VIPS) rovides branded products to consumers in China through flash sales on its vipshop.com Web site. This stock closed up 9.3% to $47.89 in Monday's trading session.