NEW YORK ( TheStreet) -- Small-caps were in the red on Tuesday morning, with the Russell 2000 down 0.6% in forenoon trading even as the broad-based S&P 500 turned positive.

Still, a handful of small-cap stocks were making big moves on unusual volumes.

Texas-based Sterling Bancshares ( SBIB) was soaring 16% to $9 after Comerica ( CMA) said it would acquire the bank for a little over $1 billion, or $10 per share, a 30% premium over Sterling's closing price on Friday. The announcement followed earlier reports that Sterling's management was soliciting bids for a takeover.

Sterling had been included in TheStreet's list of 10 regional bank takeover targets in December.

Over 20 million shares were changing hands on Tuesday, against an average volume of 950,000.

Lithium battery-maker Ener1 ( HEV) was among the top gainers in the small-cap space, jumping 36% to $4.99 on volume of over 13 million. The company announced a joint venture agreement with China-based Wanxiang Electric Vehicle to produce lithium ion cells and battery packs for the rapidly growing Chinese market.

The joint venture is expected to achieve annual cell manufacturing capacity of about 40,000 electric vehicle battery packs annually by 2014.

Shares of Ariad Pharmaceuticals ( ARIA) were zooming 26% to $6.62 after it reported positive results from the Phase III trials of its oral drug, ridaforolimus. The drug helped patients with soft tissue and bone cancer remain in remission longer than a placebo, according to the results.

Ariad also said that Merck ( MRK) will be filing for marketing approval in 2011.

Shares of Datalink ( DTLK) hit a 52-week high on Tuesday after it said that it expects to significantly exceed its previous fourth-quarter earnings and revenue estimates.

The company expects earnings per share to be in the range of 15 cents to 18 cents. Adjusted for items, the company expects earnings per share in the range of 21 to 24 cents. Its previous guidance was for a earnings per share in the range of 9 cents to 13 cents, and non-GAAP earnings to be in the range of 12 to 16 cents.

Israel-based Pluristem Therapeutics ( PSTI - Get Report), a bio-therapeutics company engaged in stem-cell research, said it had won U.S. and European approval to conduct advanced trials for its treatment of peripheral artery disease. Shares surged 15% to $3.14 on volumes of 2.3 million.

Samson Oil & Gas ( SSN), Euro Tech Holdings ( CLWT) and Northern Dynasty Minerals ( NAK) were some of the other major movers on Tuesday trading.

-- Written by Shanthi Bharatwaj in New York

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