His father Pekka Herlin died in 2003, and it was discovered that he had rewritten his will in 1999, leaving most of the elevator and escalator maker Kone to his brother Antti Herlin. Ilkka and his siblings Ilona and Niklas were unhappy about not being informed, and the dispute finally ended in 2005. The Kone company was split, with Antti receiving a majority stake in its core elevator business. Ilkka and his siblings received a majority of Cargotec and a minority stake in the new Kone company. All four siblings became billionaires.