Silverfleet Capital’s annual European Buy and Build Monitor tracks this add-on activity across the world.
Over the course of the year, it tracked 404 such transactions compared with 393 in 2014.
The total was boosted by 125 deals in the third quarter of 2015, which was the most active three-month period since 2008.
The report noted a strong performance from the UK and Ireland, with 86 transactions tracked, up five per cent on 2014.
Add-on activity in North America, meanwhile, was down 30 per cent and the Asia-Pacific region saw a 27 per cent fall.
The average disclosed value in 2015 was £40.5m.
The largest UK deal saw Park Resorts, which is owned by private equity group Electra Partners, merge with rival Parkdean Holidays to create a £960m camping and caravaning giant with 73 sites across the UK.
Neil MacDougall, managing partner of Silverfleet Capital, said: “The UK and Ireland was the most active region and seven of the 12 deals over £60m were completed by UK-based platform companies.
"Our analysis of active platform companies starts to show why buy and build is so popular with private equity GPs and LPs and we expect this trend to continue over 2016.”