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.

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 recently.

Dollar Tree

Dollar Tree (DLTR) - Get Report operates discount variety stores in the U.S. and Canada. This stock is trading up 29% to $69.49 in Thursday's trading session.

Thursday's Volume: 4.04 million
Three-Month Average Volume: 2.50 million
Volume % Change: 375%

From a technical perspective, DLTR is ripping sharply higher here right off its 50-day moving average of $67.49 with strong upside volume flows. This sharp move to the upside is now quickly pushing shares of DLTR within range of triggering a big breakout trade. That trade will hit if DLTR manages to take out some key near-term overhead resistance levels at $71.20 to its 52-week high at $71.53 with high volume.

Traders should now look for long-biased trades in DLTR as long as it's trending above its 50-day at $67.49 or above some more key near-term support at $65.20 and then once it sustains a move or close above those breakout levels with volume that registers near or above 2.50 million shares. If that breakout begins soon, then DLTR will set up to enter new 52-week-high territory, which is bullish technical price action. Some possible upside targets off that breakout are $75 to $80.

eBay

eBay (EBAY) - Get Report provides online platforms, tools and services to help individuals and merchants in online and mobile commerce and payments in the U.S. and internationally. This stock is trading up 3.9%% to $55.51 in Thursday's trading session.

Thursday's Volume: 10.50 million
Three-Month Average Volume: 8.14 million
Volume % Change: 291%

From a technical perspective, EBAY is gapping sharply higher here back above its 50-day moving average of $55.30 with strong upside volume flows. This strong gap to the upside is now quickly pushing shares of EBAY within range of triggering a major breakout trade. That trade will trigger if shares of EBAY manage to take out some key near-term overhead resistance levels at $56.43 to $57.94 with high volume.

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Traders should now look for long-biased trades in EBAY as long as it's trending above Thursday's intraday low of $54.77 or above its 200-day moving average of $52.94 and then once it sustains a move or close above those breakout levels with volume that hits near or above 8.14 million shares. If that breakout triggers soon, then EBAY will set up to re-test or possibly take out its next major overhead resistance level at its 52-week high of $59.70. Any high-volume move above $59.70 will then give shares of EBAY a chance to trend north of $60.

Ardelyx

Ardelyx (ARDX) - Get Report discovers, develops and commercializes non-systemic small molecule therapeutics for the gastrointestinal tract to treat cardio-renal and metabolic diseases. This stock is trading up 3.7% at $25.94 in Thursday's trading session.

Thursday's Volume: 54,000
Three-Month Average Volume: 65,397
Volume % Change: 132%

From a technical perspective, ARDX is ripping higher here right off its 50-day moving average of $24.41 with decent upside volume flows. This stock has been uptrending over the last few weeks, with shares moving higher from its low of $18.13 to its intraday high of $26.41. During that uptrend, shares of ARDX have been consistently making higher lows and higher highs, which is bullish technical price action. That move is now pushing shares of ARDX within range of triggering a near-term breakout trade. That trade will hit if ARDX manage to take out some key near-term overhead resistance at around $28 with high volume.

Traders should now look for long-biased trades in ARDX as long as it's trending above its 50-day moving average of $24.41 or above some more near-term support at $22 and then once it sustains a move or close above those breakout levels with volume that hits near or above 65,397 shares. If that breakout develops soon, then ARDX will set up to re-test or possibly take out its next major overhead resistance levels $31.52 to its all-time high at $35.48.

Healthstream

Healthstream (HSTM) - Get Report provides suite of software-as-a-service solutions for the healthcare industry in the U.S. This stock is trading up 2.5% at $28.14 in Thursday's trading session.

Thursday's Volume: 211,000
Three-Month Average Volume: 145,965
Volume % Change: 293%

From a technical perspective, HSTM is trending higher here right above some key near-term support levels at $27.10 to $27.02 with above-average volume. This stock has been trending sideways and consolidating over the last month and change, with shares moving between $27.02 on the downside and $30.45 on the upside. This spike to the upside on Thursday is now starting to push shares of HSTM within range of triggering a near-term breakout trade above a key downtrend line. That trade will hit if HSTM manages to clear some key near-term overhead resistance levels at $28.81 to its 50-day moving average of $29.01 and then above more near-term resistance at $29.65 with high volume.

Traders should now look for long-biased trades in HSTM as long as it's trending above some key near-term support levels at $27.10 to $27.02 or above its 200-day moving average of $26.32 and then once it sustains a move or close above those breakout levels with volume that hits near or above 145,965 shares. If that breakout materializes soon, then HSTM will set up to re-test or possibly take out its next major overhead resistance levels at $30.45 to its 52-week high at $32.17. Any high-volume move above its 52-week high will then give HSTM a chance to tag $35.

-- Written by Roberto Pedone in Delafield, Wis.

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At the time of publication, author had no positions in stocks mentioned. Roberto Pedone, based out of Delafield, Wis., is an independent trader who focuses on technical analysis for small- and large-cap stocks, options, futures, commodities and currencies. Roberto studied international business at the Milwaukee School of Engineering, and he spent a year overseas studying business in Lubeck, Germany. His work has appeared on financial outlets including CNBC.com and Forbes.com. You can follow Pedone on Twitter at www.twitter.com/zerosum24 or @zerosum24.