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 Trades to Profit From a January Rally 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 that were rising on unusual volume Wednesday. Martin Midstream Partners LP Martin Midstream Partners LP ( MMLP) provides terminal ling and storage services for petroleum products and by-products, natural gas services, sulfur and sulfur-based products, and marine transportation services. The stock closed up 2.8% at $31.93 on Wednesday. Wednesday's Volume: 282,000 Average Volume: 137,027 Volume % Change: 156% From a technical perspective, MMLP gapped higher Wednesday right above some near-term support at $30.50 with above-average volume. This stock has been trending sideways for the last month, with shares moving between $30.03 on the downside and $31.50 on the upside. The stock has now started to move above the upper-end of that recent range with solid volume, which is now quickly pushing MMLP within range of triggering a near-term breakout trade. That trade will hit if MMLP manages to take out its 50-day at $32.04 and its 200-day at $32.36 with high volume. Traders should now look for long-biased trades in MMLP as long as it's trending above $31, and then once it sustains a move or close above those breakout levels with volume that hits near or above 137,027 shares. If that breakout triggers soon, then MMLP will set up to re-test or possibly take out its next major overhead resistance levels at $33.27 to $34.50.