Potential investors in buy-out group Kohlberg Kravis Roberts' new €3.5bn ($4.5bn) European fund are worried about the lack of a guaranteed minimum return.

A Scandinavian pension fund investor described KKR's terms and conditions for the fund as "aggressive". A large European fund of funds manager added that European investors were uncomfortable with the absence of a clause fixing a return that KKR must make before it can take a share of the profits.