The Surrey-based company runs 17 events and holds 12 trade publications, serving the coatings, chemicals, commodities, glass and primary metals sectors.
The sale, scheduled for completion by the middle of next month, will not include The Middle East Coatings Show, which will be owned by DMG and run on its behalf by QBM.
"Our Redhill-based business is a good one on its own, but as our strategic direction has taken us away from publishing, we decided to sell it," said DMG World Media chief executive officer Mike Cooke.
"We are delighted to have found a buyer who will keep the business together and continue to run it from Redhill."
QBM owners Paul Michael and Keith Harris added: ''Both Paul and I have worked in this business, so we know it well. There is a great team of people with an excellent range of products.''
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