NEW YORK ( TheStreet) -- Several small-cap stocks were moving on above-average volume during Friday's session.

Purple Communications ( PRPL) plummeted by 80 cents, or nearly 50%, to 81 cents after the company late Thursday said it will voluntarily delist from the Nasdaq as part of its strategy to conserve resources and manage costs and administrative burden. Volume topped 306,000 shares, compared to the 50-day average daily volume of 12,000, according to the Nasdaq.

NightHawk Radiology Holdings ( NHWK) dropped by $1.58, or 23.4%, to $5.18 after the company late Thursday offered weak guidance for the fourth quarter, saying it expects earnings of 8 cents to 10 cents a share on revenue of $38 million to $40 million, compared to the Thomson Reuters average estimate for earnings of 15 cents a share on revenue of $40.13 million. Volume topped 3 million shares, compared to the 50-day average daily volume of 174,000, according to the Nasdaq.

U.S. Concrete ( RMIX) tumbled by 13 cents, or 10.7%, to $1.09 after the company late Thursday posted a third-quarter revenue of $153.6 million, compared to the Thomson Reuters average estimate for sales of $158.1 million. Volume topped 1.1 million shares, compared to the 50-day average daily volume of 176,000, according to the Nasdaq.

Move, Inc. ( MOVE) fell by 26 cents, or 13.6%, to $1.65 after the company late Thursday that it expects full-year 2010 revenue of $184 million to $192 million, well below the Thomson Reuters average estimate of $230.7 million. Analysts expect sales of Volume topped 3 million shares, compared to the 50-day average daily volume of 499,000, according to the Nasdaq.

Sonic Solutions ( SNIC) jumped by $1.08, or 16.9%, to $7.46 after the company late Thursday posted a third-quarter net loss of a penny a share, compared to the Thomson Reuters average estimate it would record a quarterly loss of 5 cents a share. Volume topped 1 million shares, compared to the 50-day average daily volume of 241,000, according to the Nasdaq.

-- Written by Robert Holmes in New York.

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