6 Stocks Rising on Unusual Volume

NEW YORK (Stockpickr) -- Professional traders don't just look at a stock's price moves; they also look for big changes in volume.

Major moves in volume can signal unusual activity, such as insider buying or selling -- or buying or selling by "superinvestors."

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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.

99 Cents Only Stores (NDN) is engaged in the sale of various consumer products through its retail stores at price points of mainly 99.99cent or less. The stocks is trading up 4.4% at $21.39 in recent trading.

Volume: 23.1 million

Average Volume: 785,300

Volume % Change: 2,803.8%

99 Cents Only Stores agreed to be acquired for $22 a share, or $1.6 billion. 99 Cents is one of TheStreet Ratings' top-rated multiline retail stocks.

Superior Energy Services (SPN) is a provider of specialized oilfield services and equipment focusing on serving the production-related and drilling-related needs of oil and gas companies. The stock is trading up 1.3% at $23.93 in recent trading.

Volume: 5.2 million

Average Volume: 1 million

Volume % Change: 391%

Superior Energy is one of the tiop holdings at David Dreman's Dreman Value Management and was one of Jefferies' four best energy stocks for 2011.

Endocyte (ECYT) is a biopharmaceutical company developing targeted therapies for the treatment of cancer and inflammatory diseases. The stocks is trading up 5.1% at $11.03 in recent trading.

Volume: 477,036

Average Volume: 207,800

Volume % Change: 129.6%

BigBand Networks (BBND) develops, markets and sells network-based solutions that enable cable operators and telecommunications companies to offer video services across coaxial, fiber and copper networks.. The stocks is trading up 74% at $2.21 in recent trading.

Volume: 27.6 million

Average Volume: 282,800

Volume % Change: 9,634.8%

BigBand Networks will be acquired by Arris Group(ARRS) for $2.24 a share. It also shows up on a list of today's Biggest & Gainers.

Synergetics USA (SURG) is a medical device company that designs, manufactures and markets innovative microsurgical instruments and other devices. The stocks is trading up 7% at $6.10 in recent trading.

Volume: 328,512

Average Volume: 110,800

Volume % Change: 196.5%

Synergetics is set to announce earnings Tuesday after the market close.

MarkWest Energy Partners (MWE) is engaged in the gathering, compressing, treating, processing and transportation of natural gas; the transportation, fractionation, storage and marketing of NGLs; and the gathering and transportation of crude oil.. The stock is trading up 1.4% at $45.88 in recent trading.

Volume: 1.3 million

Average Volume: 440,700

Volume % Change: 195.6%

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