NEW YORK ( TheStreet) -- Clinical Data ( CLDA) was the biggest gainer among small-caps Monday afternoon, its shares soaring 55% to $23.30, after U.S. regulators approved its major depressive disorder treatment Viibryd. The biotech company said the drug would be available in U.S. pharmacies by the second quarter. Over 9 million shares changed hands.

Shares of Genoptix ( GXDX) jumped 26% to $24.83 on heavy volumes after Swiss pharma giant Novartis ( NVS) said it was acquiring the diagnostics laboratory for $470 million or $25 per share in an all cash deal.

Rexahn Pharmaceuticals ( RNN) shot up 20% to $1.57 after Israel-based Teva Pharmaceuticals ( TEVA) said it had acquired a 6% stake in the company at $1.69 per share.

Several solar stocks were shining on the bourses after Goldman Sachs added First Solar ( FSLR - Get Report) to its conviction list. Shares of LDK Solar ( LDK) were surging 10.5% to $14.53. Solarfun Power ( SOLF), Trina Solar ( TSL) and ReneSola ( SOL - Get Report) were also up sharply.

Shares of Depomed ( DEPO) were recovering Monday after plunging last week, rising 7.2% to $6.23. The stock took a hit last week after it said that Abbot Laboratories ( ABT) was reluctant to market its pain reliever drug.

Level 3 Communications ( LVLT), Dot Hill Systems ( HILL), Pluristem Therapeutics ( PSTI) and ATP Oil and Gas ( ATPG) were among the other major gainers on Monday.

-- Written by Shanthi Bharatwaj in New York

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