Taiwan-based smartphone maker HTC has downgraded its revenue outlook for the fourth quarter of 2011, saying its original outlook “is not applicable”. Due to “macro economic downturn and market competition,” the company is now forecasting revenue will be at a similar level to 2010’s fourth quarter, when it was US$3.42 billion. The new revenue forecast is approximately 20 percent lower than previously forecast and represents a 23 percent decline compared to the record revenues posted by the company for Q3.

Following the news, HTC’s shares fell to their lowest levels for 16 months, according to the Financial Times, with a 6.9 percent dip to US$18.43.

The company – which is the world’s fifth largest smartphone maker by sales – said in a statement that despite Q4 revenue not being what it expected, it has confidence that its products – including a number of LTE-enabled devices expected to be unveiled before the end of the year – will lead to a return to revenue growth during the first half of 2012.

HTC has also published a statement regarding the US International Trade Commission’s ruling that Apple hasn’t infringed patents owned by HTC acquisition target, S3 Graphics. The statement said S3 Graphics will continue to appeal the decision. “In light of recent developments, HTC will work closely in good faith with VIA Technologies and WTI Investment International to conduct holistic re-evaluation of the S3 Graphics acquisition,” the statement added.