Questions for Case at the AQR’s Momentum Funds (The Momentum Effect) Is it important to know the economic explanation of a profitable investment strategy? In other words, why not just simply invest in some ideas like momentum and make money without caring too much about its underlying reasons? Is Momentum a risk or a behavioral bias rooted in human minds? Is market efficient or not efficient given momentum is there? What are the criterions for you to judge whether the price/return of momentum portfolios is efficient?