Rising 5.4%, the share price touched a high of 332p as the market shrugged off the group's mixed performance in the Rajars for July-September, which saw GCap's London flagship station Capital fall behind competitors Heart and Magic.
Private equity buyers are believed to be prepared to pay more than Friday's closing price of 315p, although they did not move on GCap when it hit a low of 258p in June.
Cinven, 3i and Permira have been reported to be studying GCap and to have engaged advisers from the radio industry.
Tim Schoonmaker, the long-time head of Emap's radio business until January 2004, is believed to be advising a private equity group.
3i last year bid for Scottish Media Group's Virgin Radio as part of a team put together by Lord Alli, but was rebuffed by SMG.
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