Robert Jeremy Goltho Grantham is a British investor and the co-founder and chief investment strategist of GMO LLC, a Boston-based asset management firm. GMO managed over US$118 billion in assets as of March 2015, a figure that later adjusted to $65 billion by December 2020. Grantham is recognized for establishing one of the world's first index funds in the early 1970s and was included in Bloomberg Markets magazine's 50 Most Influential ranking in 2011.