Troubled software maker Sega, the parent of Sonic the Hedgehog, has dismissed reports of merger talks with either US games group Electronic Arts (EA) or Microsoft.
Sonic has been unable to keep up Sega sales
"It is not true at all that Electronic Arts of the United States has sounded us on a capital tie-up," Sega president Hideki Sato said in a statement.
Sega insisted it would pursue a previously announced tie-up with a local pin-ball machine maker.
The denials sent shares tumbling back down 5% after press speculation about a merger last week saw them rocket up more than 15% higher on Friday.
Microsoft and EA have both denied the reports.
On 13 February, Sega and Sammy, Japan's largest maker of pinball-style "pachinko" machines, announced they would integrate their businesses by October and would consider a full merger.
"We will give the top priority to the earlier-announced integration of operations with Sammy and work towards it," the company said.
But the Sega-Sammy tie-up is seen as a takeover by the pinball giant and has been rejected by Sega's investors.
Sega reported its fifth successive full-year loss in 2001-02 and last year ditched its loss-making Dreamcast console.