A U.S. trade panel ruled in favor of Apple on Friday, saying the Taiwanese company had infringed two of its patents.
In a bid to limit the impact on its shares, HTC said over the weekend that it would buy back up to 20 million of its own shares within the next two months.
But the announcement failed to stem the fall of its share price, sparked by concern it could face a huge compensation payout to Apple.
Rivals like Samsung are also nipping at the heels of HTC, and slowing global demand has raised questions about the sector’s outlook.
HTC is set to provide guidance for the third quarter at the end of this month.
The ruling marks the first step in several on-going disputes between Apple, Samsung and HTC in the cutthroat smartphone market.
A final determination of the case is due on December 6.
Bottom line: Shares of Taiwan smartphone-maker, HTC, tumble, as investors ignore a share buyback, and focus on a patent ruling favoring rival, Apple Inc.