Private equity group Kohlberg Kravis Roberts on Tuesday filed with US regulators to raise up to $1.25bn in a flotation that will allow it to match the pioneering move into the public markets made last month by Blackstone, its main rival.

The move by KKR, one of the oldest and largest US private equity groups, comes amid concerns that the cheap credit that has fuelled the buy-out boom may be coming to an end. It also comes amid increased political scrutiny of the private equity industry.