Private equity firms are increasingly focusing on bolt-on deals, where they help portfolio companies to reach scale, as they seek to boost profits and avoid paying high prices in the main buyout market.

Bolt-on deals have comprised 45% of European private equity purchases so far this year, according to Dealogic, a figure that has been rising steadily since 2003. There have been 234 bolt-on deals in Europe made by private equity firms so far this year, putting it on course to beat last year's record of 557.