Kohlberg Kravis Roberts said it named Alexander Navab as sole leader of the firm's Americas private equity business, which he previously co-headed with Michael Michelson, according to a memorandum sent to investors that was viewed by The Wall Street Journal on Thursday.

Michelson, who had co-led the Americas private equity business alongside Navab since 2008, will focus on investing and portfolio company management, according to the memo. Michelson will continue to serve on KKR's management committee and the Americas private equity group's investment committee.