As Global considers whether to improve its offer, The Times has reported a source close to GCap as saying Global would have to offer a price that started with a two and "if they raised it by 10% it would still be too low to initiate discussions".
GCap's key shareholders are institutional investors Fidelity and Schroders, which each own 15%, and the Daily Mail & General Trust.
Shareholders are understood to be angry that they were not informed of Global's December 17 bid, which offered a 21% premium on GCap's average share price over the past three months and a 50% premium to its January 4 closing price of 121p.
However, they may be willing to give new chief executive Fru Hazlitt time to prove GCap's assertion that Global's bid undervalues the company.
Hazlitt is presenting her strategy to shareholders in early February and, according to reports, will not be pressured into bringing the meeting forward because of the approach.
Global, which is chaired by former ITV chief executive Charles Allen, is attempting to join its Heart and Chrysalis brands with GCap brands such as Classic FM and Capital after losing out in the bidding for Emap's radio assets, among them Magic.
Yesterday, GCap's shares leapt ahead by as much as 50% hitting 182p. This morning, they remain buoyant, trading at 178p.