Robert D. Arnott (born June 29, 1954[1]) is an American businessman, investor, and writer who focuses on articles about quantitative investing.

[5] Topics of these papers have included the following: mutual fund returns, the equity risk premium, tactical asset allocation, and alternative index investing.

[14] In November, 2009, Research Affiliates was granted a patent for their index methodology that selects and weights securities using fundamental measures of company size.

[16] This fund is intended to feature what Arnott calls "Third Pillar" options, meant to diversify beyond mainstream stocks and investment-grade bonds, and may include master limited partnerships, high-yield bonds, emerging markets debt, or liquid alternatives with the goal of boosting long-term portfolio performance.

[18] In 2015, Arnott donated $100,000 to America's Liberty PAC, a political action committee formed in support of Representative Rand Paul's 2016 presidential bid.