In another sign of trouble at HTC, the Taiwan-based smartphone maker started downsizing its U.S. operations on Friday, cutting an undisclosed number of staff.

The move is meant to "streamline and optimize" the company's U.S. organization "after several years of aggressive growth," HTC said in a Monday email. A company spokeswoman declined to specify how many employees would be affected.

"However, to achieve our long-term goals as a business and return maximum value to our shareholders, this is a necessary step to drive ongoing innovation," the company said.

HTC has been facing a difficult year on weak earnings that have sent its stock price tumbling. In the second quarter, its net profit plummeted 83 percent year-over-year, despite strong reviews for its flagship smartphone, the HTC One.

The weak financials are major change from only a couple years ago when HTC was riding high selling Android smartphones in the U.S. But starting in late 2011, the company's net profit has sagged on increased competition from Samsung and Apple.

To recover, HTC has focused on building up its "One" smartphone brand. In addition, the company has expanded its China presence, and in August launched a new marketing campaign that's enlisted Hollywood actor Robert Downey Jr.

While the company has largely focused selling high-end handsets, in July HTC said it was planning on selling more mid-tier and entry level phones to regain market share. The new phones will launch at end of the third quarter or early fourth quarter.

But the company's troubles go beyond issues with smartphone sales and marketing. In September, Taiwanese authorities arrested three HTC employees for allegedly stealing company secrets. One of the employees arrested was Thomas Chien, HTC's vice president of product design.

HTC has declined to offer further details on the case.