Events organiser UBM has agreed to be acquired by rival Informa by way of a cash and shares deal.
UBM shareholders would receive 1.083 Informa Shares and 163p in cash for each of their UBM shares.
Based on the closing price of both company's shares on January 15, the offer represented a 30% premium to its market value, UBM said.
"Discussions between the parties remain ongoing regarding the other terms and conditions of the proposed combination, satisfactory completion of due diligence and final approval by the boards of Informa and UBM," UBM said.
"Subject to the ongoing discussions, the boards of Informa and UBM expect to recommend the proposed combination to their respective shareholders.
The combined group would be around 65.5% owned by Informa shareholders and around 34.5% by UBM shareholders.