Stock Quotes in this Article: AFOP, VNET, RDA

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.

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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.

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With that in mind, let's take a look at several stocks rising on unusual volume today.

RDA Microelectronics

RDA Microelectronics (RDA) is a China-based fabless semiconductor company that designs, develops and markets radio-frequency and mixed-signal semiconductors for a broad range of cellular, broadcast, and connectivity applications. This stock closed up 5.2% at $11.74 on Friday.

Friday's Volume: 288,000

Average Volume: 134,219

Volume % Change: 100%

Shares of RDA ripped higher on Friday on encouragement from a Needham analyst to buy the stock after chipmaker Spreadtrum (SPRD) agreed to be acquired.

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From a technical perspective, RDA trended higher here right above some near-term support at $11 with above-average volume. This move is quickly pushing shares of RDA within range of triggering a major breakout trade. That trade will hit if RDA manages to take out some near-term overhead resistance levels at $11.72 to $11.80 with high volume.

Traders should now look for long-biased trades in RDA as long as it's trending above its 50-day at $10.62 and then once it sustains a move or close above those breakout levels with volume that hits near or above 134,219 shares. If that breakout triggers soon, then RDA will set up to re-test or possibly take out its 52-week high at $12.58. Any high-volume move above $12.58 will then give RDA a chance to tag its next major overhead resistance levels at $12.77 to $13.83.

21Vianet Group

21Vianet Group (VNET) is a carrier-neutral Internet data center service provider that provides hosting and related services, managed network services and cloud computing infrastructure services. This stock closed up 8.2% at $12.84 on Friday.

Friday's Volume: 1.10 million

Average Volume: 348,862

Volume % Change: 209%

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From a technical perspective, VNET ripped sharply higher here right above some near-term support at $11.30 with heavy upside volume. This stock has been uptrending strong for the last two months, with shares soaring higher from its low of $8.52 to its new 52-week high at $13. During that move, shares of VNET have been mostly making higher lows and higher highs, which is bullish technical price action. That move has now pushed shares of VNET within range of triggering a key breakout trade. That trade will hit if VNET manages to take out some past overhead resistance levels at $13.63 to $13.75 with high volume.

Traders should now look for long-biased trades in VNET as long as it's trending above some near-term support at $11.30 and then once it sustains a move or close above those breakout levels with volume that hits near or above 348,862 shares. If that breakout triggers soon, then VNET will set up to re-test or possibly take out its next major overhead resistance levels at $14.82 to $17.

Alliance Fiber Optic Products

Alliance Fiber Optic Products (AFOP) designs, manufactures and markets a range of fiber optic components, and integrated modules incorporating these components, for communications equipment manufacturers and service providers. This stock closed up 2% at $30.71 on Friday.

Friday's Volume: 346,000

Average Volume: 163,770

Volume % Change: 78%

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From a technical perspective, AFOP spiked notably higher here with above-average volume. This stock has been uptrending strong for the last six months, with shares soaring higher from its low of $10.56 to its recent high of $32.34. During that uptrend, shares of AFOP have been consistently making higher lows and higher highs, which is bullish technical price action. This stock has also seen extremely bullish upside volume flows for the entire month of July. Shares of AFOP are now starting to move within range of triggering a near-term breakout trade. That trade will hit if AFOP manages to take out its 52-week high at $32.34 with high volume.

Traders should now look for long-biased trades in AFOP as long as it's trending above $28 and then once it sustains a move or close above it 52-week high at $32.34 with volume that this near or above 163,770 shares. If that breakout triggers soon, then AFOP will set up to enter new 52-week high territory, which is bullish technical price action. Some possible upside targets off that breakout are $35 to $40.

To see more stocks rising on unusual volume, check out the Stocks Rising on Unusual Volume portfolio on Stockpickr.

-- 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.