Pamplona Capital Management, an alternative investor, is preparing to close its second mid-market buyout fund at almost five times the amount it raised two years ago in what would be one of the largest increases between funds raised by a private equity firm.

The London-based firm is expected shortly to hit its hard cap of €1.5bn ($2.1bn) for its second private equity fund, Pamplona Capital Partners II, following an annual performance rate of more than 100% for its first fund since its inception in 2005. Pamplona Capital Partners I raised €322m.