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

>To contact the writer of this article, click here: Shanthi Bharatwaj.

>To follow the writer on Twitter, go to

>To submit a news tip, send an email to:

Disclosure: TheStreet's editorial policy prohibits staff editors and reporters from holding positions in any individual stocks.