Polycom Inc.'s (PLCM) fourth-quarter earnings rose a greater-than-expected 50% as the videoconferencing company's emerging-market sales continued to outperform its American business.

Shares jumped 4.9% to $19.32 after hours Monday as revenue also topped expectations. The stock had slid in recent months since hitting a 10-year high of $34.30 in July.

Polycom's revenue growth, though sharp, has eased in recent quarters .