The deal, announced this morning, is the latest stage in UBM's move away from traditional B2B publishing to focus on events, marketing and data products.
Briefing Media will pick up titles including Farmers Guardian, Dairy Farmer, Pulse and Practical Commissioning – plus their associated websites – and a number of medical events and seminars.
The farming and medical groups employ 90 staff in total, based in Preston and London, and generated £12.1 million in revenue last year. UBM has held on to Chemist and Druggist magazine, data products and the Cropworld conference.
UBM chief executive David Levin said in today's stock market alert: "I am very pleased we have passed these successful UK magazine titles to a new management team who will provide the focused leadership and investment to ensure their continued success.
"I would like to thank our teams in Preston and in London for their contribution to UBM over the years and wish them and their new management teams well for the future."
He added: "These transactions also mark a further significant step in the transformation of UBM into a set of events and other B2B marketing, communications, and data services businesses serving attractive global communities across a variety of media."
The new owner, Briefing Media, was founded by Neil Thackray and Rory Brown in 2010. It runs TheMediaBriefing site which provides analysis, comment, aggregation and events for the media industry.
The company said in a statement that it would "invest in the titles to grow their market position both on and offline. We also plan to accelerate the portfolio of digital, data-led products and physical events".
Thackray said: "When we founded Briefing Media we had a vision for creating a vibrant new business-to-business media company. This acquisition gives us both the scale and market opportunity to accelerate that ambition.
"We are delighted to be acquiring assets with such excellent pedigrees and reputations in important business markets and to be working with GCP Capital Partners. This will be the first but not the last acquisition we plan to make."
The group's expansion has been funded by private equity firm GCP Capital Partners, who will join the Briefing Media board. The deal is expected to be completed within four to six weeks.