Fitness gadget-maker Fitbit tumbled 16% in after-hours trading, with investors disappointed by the company’s guidance for the current quarter. Fitbit is forecasting $420 million to $440 million in revenue for the current quarter and adjusted earnings per share is expected to be between zero and two cents.

Yet San Francisco-based Fitbit announced significantly better-than-expected earnings for the fourth quarter of last year. The company posted 35 cents per share during holiday season, well above analyst estimates of 25 cents per share, and the 21 cents per share reported in the same period last year.  Fitbit also brought in $712 million in revenue, which surpassed analyst estimates of $648 million, and nearly doubled the $370 million in sales seen in fourth quarter 2014.

While the company has managed to excel in the fitness tech category, growing competition from smartwatches meant that some early adopters are making the switch from Fitbit to Apple Watch.

Fitbit shares are down 44% since the beginning of the year because investors did not like Fitbit’s new smartwatch that was announced at CES.

Others in the space include Misfit, which was recently acquired by Fossil, and Jawbone, which has struggled to retain significant market share.  Jawbone has filed several lawsuits against Fitbit, including patent infringement.

Fitbit went public on the New York Stock Exchange last June, pricing its shares at $20. The stock closed Monday at $16.48 and the company has a market cap of $3.4 billion.