With the exception of the period 1989–1997 when he was a professor at the University of Minnesota, Jagannathan has been at Kellogg since graduate school.
Jagannathan received a bachelor's degree in mechanical engineering from the College of Engineering, Guindy of University of Madras in 1970, an MBA from the Indian Institute of Management Ahmedabad, India and his Ph.D. from Carnegie Mellon University.
His research interests are in the areas of asset pricing, capital markets and financial institutions.
Along with Zhenyu Wang, in 1996 he advanced a variation on the capital asset pricing model known as "conditional CAPM."
He is also among those known for the Hansen–Jagannathan bounds, which provide a way to use security market data to restrict the volatility of the stochastic discount factor.