The deal was announced on 25 March and involves a conditional agreement to acquire Last Word for an initial consideration of £8m ($10.6m, €9.3m).
The maximum payable, subject to certain earnings thresholds being met, is £20m.
Bonhill focuses on three sectors: technology, diversity and financial services.
Its financial titles include consumer brands What Investment and Growth Company Investors in the UK, as well as InvestmentNews in the US.
The firm also runs a range of diversity-led events, including the global Women in IT and Women in Finance series.
Following completion of the deal, the two companies will have asset and wealth management brands in America, Europe, the UK, southern Africa and Asia.
Simon Stilwell, chief executive of Bonhill, commented: “We are pleased to announce the acquisition of Last Word, a leading international B2B media business servicing the global asset management sector.
“Bringing our two businesses together will enable Bonhill to provide a truly global sales and marketing proposition to the international asset management community and provides the opportunity to leverage InvestmentNews‘ presence and platform to expand its existing propositions in the US.
“These are exciting times for the company and we look forward to the period ahead.”
No senior changes
Last Word co-founders Rod Boulogne (chief executive), Jamie Hinchliffe (group managing director), Dylan Emery (editorial director) and Tom Porter (Asia managing director) will all remain in their respective roles.
They describe the primary motivation behind the sale as “ensuring that Last Word can develop to its full potential for the benefit of our growing client base and, vitally, our fantastic team”.
“We firmly believe that the combination with Bonhill will provide the necessary support, funding, infrastructure and skills to maximise the potential of our existing brands and those in development.”
As a strong sign of confidence in the combined group, the Last Word partners have taken a £2m of the initial consideration of the sale proceeds in Bonhill shares.