The CEO of Norges Bank Investment Management, the world's biggest single owner of public equities, says a fund of its size needs to be widely diversified across asset classes, because tactical asset allocation would be "very, very tough." Nicolai Tangen, who runs the $1.8 trillion sovereign wealth fund, also talks about his investment concerns and AI. Tangen speaks on "The David Rubenstein Show: Peer-to-Peer Conversations." This interview was recorded January 22 at the Bloomberg House in Davos.