Advent International will today cement its position as the world's biggest mid-market private equity firm with the news it has raised a new €6.6bn ($10.3bn) fund, highlighting investors' appetite for medium-sized buy-outs.

The amount raised is a sign that investors are looking to put more money with private equity firms that are more likely to do deals in the near term. The "mega buy-out" firms are hampered by the crisis in debt markets, while mid-sized buy-outs are less reliant on plentiful supplies of cheap credit.