Shares in the world's No.5 handset maker, HTC Corp, tumbled more than 4 percent on Tuesday, after Apple Inc sued the company in a fresh complaint with a U.S. trade panel.

Fund managers said investors sold off HTC in a market that was already reacting to unconfirmed speculation.

There are rumors out there that HTC would need to pay Apple T$20 billion ($693.64 million) in compensation, but the truth is the preliminary determination of the lawsuit shouldn't involve any monetary compensation. said Mike Fang, a fund manager of Paradigm Asset Management Co.

Apple Inc filed its latest complaint against HTC with a U.S. trade panel over unspecified portable electronic devices and software, according to the panel's web site.

Last year, Apple filed a separate action against HTC with the U.S. International Trade Commission, where HTC then leveled its own patent infringement claims against Apple. Preliminary rulings for those cases are expected this week.

By 0307 GMT, HTC was down 4.7 percent, versus the broader market's 1.72 percent drop.

Shares of the Taiwanese smartphone maker have shed more than 13 percent since last Wednesday, after its plan to acquire S3 Graphics raised concerns over corporate governance.

HTC said its net profit doubled in the second quarter, beating market expectations. But analysts suggested that because the operating income tracked forecasts, they expected shares of HTC would consolidate before the investor conference at the end of this month, when the company gives guidance for the third quarter.

(Reporting by Clare Jim; Editing by Ken Wills)