Senior buyout executives at the annual SuperReturn conference in Berlin have cast doubts over how many of the planned private equity-backed initial public offerings will succeed this year.

John Singer, chairman of Advent International, said: "I will be fascinated to see all the [planned] IPOs get through a tiny window. You would need every window in the Palace of Versailles to get all the IPOs through. We are likely to see some stickiness in exits and some selectivity from investors.