The plan would value the storied private equity firm at $12 billion to $15 billion and is part of a complex deal in which it will buy its publicly traded affiliate, KKR Private Equity Investors.

The deal gives NYSE Euronext a lead in the race against its British and German rivals to become a truly global stock exchange at a time when growth has slowed in their home markets.

The deal gives NYSE Euronext a lead in the race against its British and German rivals to become a truly global stock exchange at a time when growth has slowed in their home markets.