TOKYO Aug 18 (Reuters) - Chugai Pharmaceutical Co Ltd shares rose 21 percent to a record high following a media report that Roche Holding AG is in talks to buy the almost 40 percent stake in the Japanese firm that it doesn't already own for about $10 billion.
Shares of Chugai were up 20 percent at 3,985 yen as of 0106 GMT after touching 4,015 yen, exceeding the previous record of 3,510 yen set last month.
The Swiss group could announce a deal to take full control of its Japanese partner for oncology and arthritis drugs as early as this week, although no final decision has been made, Bloomberg reported.
In a statement, Chugai denied it was holding such discussions with Roche, while a spokeswoman for Roche declined to comment on the report. (Reporting by Chris Gallagher; Editing by Edmund Klamann)