Taiwan smartphone maker HTC Corp. has cut its fourth quarter revenue forecast as the weak global economy hurts sales and Samsung Electronics Co. steps up competition.

HTC operates a research and development office in Durham, N.C. The company is now the No. 1 smartphone seller in the U.S.

HTC’s shares tumbled 7 percent on Thursday after its announcement that revenue for the October-December quarter would be flat compared with a year earlier.

On Ffriday, Bloomberg news reported that HTC shares fell to a 16-month low.

HTC has grown on the strength of the design of its handsets, based on Google Inc.’s Android operating system.

But it faces increasing competition from its top rival, South Korea’s Samsung, while the global economic downturn has hit sales in its two main markets, the U.S. and Europe.

HTC predicted in October that fourth quarter revenue would grow 30 percent to $4.4 billion.

HTC has predicted fast growth in China shipments.