According to reports, Apax is one of the companies that made an unsolicited bid for Emap's B2B division, which includes Construction News, Retail Week and Nursing Times.
Share prices at Emap soared by nearly 12% to 854p on Friday, following news that the publisher was undergoing a strategic review of all of its divisions, which includes its radio and consumer publishing portfolio. Emap has now appointed Lazard and Citigroup to oversee the potential sale or demerger of "some or all" of its assets.
Among the other parties believed to be interested in acquiring Emap's B2B division include United Business Media, Informa and Future Publishing, although none of the parties involved have formally commented on their interest.
If Apax was successful in acquiring Emap's business-to-business division, it would likely merge it with Incisive Media, which it acquired last year for around £200m.
The future of Emap's assets is further clouded by the ongoing search for a successor to chief executive Tom Moloney, who stepped down in May after 26 years with the company.
Emap previously said its decision to consider bids for its component divisions was prompted by "unsolicited proposals for part of the group", which has now been moved forward by Apax making an informal approach.
In a statement on Friday, Emap said: "All options to maximise shareholder value will be examined, including a possible sale or demerger of some or all of its constituent businesses."
Among the other titles in Emap's business-to-business stable include Broadcast, New Civil Engineer, Plastics and Rubber Weekly and Screen International.
In May, Emap reported a pre-tax profit plunge of 13% to £193m for the year ending March 31. The group said a strong performance across its digital and B2B portfolio gave good grounds for optimism and were in line with its expectations.