GCap's shares were changing hands for around 182p this morning following weekend reports of Global's 190p-a-share offer.
On Friday, GCap shares closed at 121p, close to their lowest level since GCap's inception in 2005.
Global approached GCap on December 17 with the all-cash offer, which valued the UK's leading radio company at just £310m and was conditional on the support of the GCap board.
However, the offer was rejected by Richard Eyre, the GCap chairman. Reports claim that some GCap shareholders were angered at not being informed of the offer, despite the unusually generous premium.
Eyre appointed Fru Hazlitt to succeed Ralph Bernard as chief executive three days after Global's offer. He is understood to want to give her time to implement her vision for the company's future.
The companies put out statements this morning with Global confirming it had made an offer and said it was "currently considering its position... and there is no certainty that any offer will be made".
GCap's statement explained that the offer was rejected because the board believed it significantly undervalued the company. It added that Hazlitt would shortly be outlining her plans.
Global is a private company owned by Irish investors including John Magnier and JP McManus and chaired by Charles Allen, the former ITV chief executive. Before making the offer for GCap, it had unsuccessfully competed in the auction for Emap Radio, losing out to German publisher H Bauer.