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. Many times when above average volume moves into 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."

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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.

Let's take a look at several stocks rising on unusual volume today. They are all recording volume in midday trading that is already at least 50% above their average trading volume for a full day.

Auxilium Pharmaceuticals

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Auxilium Pharmaceuticals ( AUXL) is a specialty biopharmaceutical company with a focus on developing and marketing products to predominantly specialist audiences, such as urologists, endocrinologists, certain targeted primary care physicians, hand surgeons, subsets of orthopedic, general, and plastic surgeons who focus on the hand, and rheumatologists. The stock is trading up 4% at $18.26 in recent trading.

Today's Volume: 748,000 shares

Average Volume: 744,889 shares

Volume % Change: 154%

Shares of AUXL are ripping higher today in a weak market after the company said it appointed Adrian Adams as president and CEO effective immediately.

From a technical standpoint, AUXL has started to break out above some near-term overhead resistance at $18.09 on heavy volume. The stock is now starting to flirt with getting back above its 200-day moving average of $19.02.

A sustained move and close above $19.02 should set this stock up to ret-test its July high of $21 in the near future.

Amgen

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Amgen ( AMGN) is an independent biotechnology medicines company and the world's largest biotechnology company. Amgen discovers, develops, manufactures and markets medicines for grievous illnesses. The stock is trading up 1% at $58.94 in recent trading.

Today's Volume: 13.6 million shares

Average Volume: 7.2 million shares.

Volume % Change: 344%

Shares of AMGN moving up today after the company said it plans to buy back around 83.3 million shares at $60 per share in a modified Dutch auction, amounting to around 9.5% of its outstanding stock.

From a technical standpoint, AMGN is now quickly approaching a major breakout if it can manage to sustain a high-volume move and close above some past overhead resistance at $58.76.

If we see that action soon, then look for AMGN to re-test its May high of $60.90 in the coming days or weeks. The volume today is well above its average action, so look for that close above $58.76.

Amgen is also one of the top-yielding drug stocks.

Coinstar

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Coinstar's ( CSTR) core offerings in automated retail include its digital video disk business, where consumers can rent or purchase movies from self-service kiosks, and its coin business, where consumers can convert their coin to cash or stored value products at coin-counting self-service kiosks. The stock is trading up 6% at $46.72 in recent trading.

Today's Volume: 1.6 million shares.

Average Volume: 1.3 million shares

Volume % Change: 195%

From a technical standpoint, CSTR is gapping up today on heavy volume above its 50-day moving average at $46.40, and it's flirting with its 200-day moving average of $47.83. Market players should now watch for a sustained high-volume move and close above the 200-day.

The volume today is very strong, so watch how CSTR closes. If we get that action, look for this stock to re-test some near-term overhead resistance at $49.50. A high-volume move above that level should setup CSTR for a big move higher in the near future.

Coinstar, one of TheStreet Ratings' top-rated consumer services stocks, is oen of the top holdings of Whitney Tilson's T2 Partners as of the most recently reported period.

Silicon Laboratories

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Silicon Laboratories ( SLAB) designs and develops analog-intensive, mixed-signal integrated circuits for a range of applications. This stock is trading up 1.6% at $43.47 in recent trading.

Today's Volume: 472,000 shares

Average Volume: 472,517 shares

Volume % Change: 114%

Shares of SLAB are trading higher today despite the fact that a UBS analyst cut his rating on the stock from to neutral from buy, but maintained his price target of $43. One of the reasons cited for the downgrade was valuation, since the stock is trading at a slight premium to its historical average.

From a technical standpoint, SLAB is starting to flirt with some near-term overhead resistance at $43.61. Market players should watch for a breakout trade to trigger if SLAB can manage to sustain a move and close above $43.61 on heavy volume.

Volume is already tracking in extremely strong today, so watch for a close over $43.61. If we get that move soon, then look for SLAB to re-test $45.10 to $45.50. A move above those levels will set this stock up to trend back towards $46 to $47 in the near future.

As of the most recently reported period, Silicon Labs shows up in Coatue Management's portfolio, comprising 2.2% of the total.

Dollar General

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Discount retailer Dollar General ( DG) offers a selection of merchandise, including consumables, seasonal, home products and apparel. This stock is trading up 2.3% at $40.39 in recent trading

Today's Volume: 2.8 million shares

Average Volume: 2.4 million shares

Volume % Change: 294%

From a technical standpoint, DG has started to bounce hard today right off its 50-day moving average of $39.23 on strong volume. Any time a stock bounces big off its 50-day with volume it should be considered bullish. Market players should how watch this stock for a breakout trade if it can manage to clear some overhead resistance levels.

Traders should look for a sustained high-volume move and close above $41.25. If that breakout hits, then DG will be trading in all-time high territory, which is very bullish for any stock.

Dollar General, which shows up on a list of 6 Holiday Retail Stocks to Watch, is one of Warren Buffett's holdings -- Berkshire Hathaway increased its position in the stock by 200% in the most recently reported quarter -- and also shows up in Steven Cohen's SAC Capital's portfolio.

Spreadtrum

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Spreadtrum ( SPRD) is a fabless semiconductor company that designs, develops and markets baseband processor, radio frequency transceiver and turnkey solutions for the wireless communications and mobile television market. This stock is trading up 10% at $22.85 in recent trading

Today's Volume: 1.4 million shares.

Average Volume: 1.5 million shares

Volume % Change: 88%

Shares of SPRD are ripping higher today after the company said its revenue may exceed previous forecasts. Spreadtrum said in a statement today that it's on track to meet or exceed its fourth-quarter revenue forecast of $188 million to $194 million.

From a technical standpoint, SPRD is starting to bounce hard right near its 200-day moving average of $19.42 today on high volume. Market players should now look for the next buy point to trigger if SPRD can sustain a high-volume move and close back above its 50-day moving average of $23.85.

If we see that action, then look for this stock to re-test some near-term overhead resistance at $27.

Domino's Pizza

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Domino's Pizza ( DPZ) is a pizza delivery company in the U.S. This stock is trading up 2.8% at $34.41 in recent trading.

Today's Volume: 464,000 shares

Average Volume: 1 million shares

Volume % Change: 50%

From a technical standpoint, DPZ is starting to break out today above some past overhead resistance at $33.70 on decent volume. Market players should now watch for a sustained high-volume move and close above $33.70 and then $35.

If we get that action, this stock will then be trading in all-time high territory, which is very bullish.

To see more stocks rising on unusual volume, including SodaStream International ( SODA), G-III Apparel Group ( GIII) and Bio-Reference Laboratories ( BRLI), check out the Stocks Rising On Unusual Volume portfolio on Stockpickr.

-- Written by Roberto Pedone in Winderemere, Fla.

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At the time of publication, author had no positions in stocks mentioned.

Roberto Pedone, based out of Windermere, Fla., is an independent trader who focuses on stocks, options, futures, commodities and currencies. He is also an outside contributor to Beconequity.com and maintains the website Maddmoney.net, which he sold to Blue Wave Advisors in 2008. Roberto studied International Business at The Milwaukee School of Engineering, and he spent a year overseas studying business in Lubeck, Germany.