Halvorsen worked in the investment banking division of
Morgan Stanley after finishing his studies. Then he moved to
Tiger Management Corp, where he was a senior managing director, as well as an analyst and director of equities, and a member of the management committee. He sat on Tiger's advisory board, and on the supervisory board of the firm's largest fund, Jaguar Fund N.V.. In 1999, Halvorsen left Tiger to co-found Viking Global Investors, an investment firm managing capital in excess of $30 billion, of which he is currently the CEO, alongside David Ott and Brian Olson. Halvorsen, Ott, and Olson are part of the group known as "
Tiger Cubs," former employees of Julian Robertson's
Tiger Management Corporation now working as hedge fund managers on their own. Viking Global's main operations cover public equity and hedge funds on the international market. ==Personal life==