Mutual funds have existed in one form or another since the eighteenth century, although the first modern mutual fund was created in 1924. By 2016, over $40 trillion was invested in mutual funds worldwide (ICI, 2017). No doubt much of the recent growth in mutual funds corresponds to the demise of the defined benefit pension plan in the USA in favor of the 401(k) and other defined contribution plans, as well as similar trends worldwide.This ebook on mutual funds deals with such a diverse set of institutions and behaviors that we are only able to cover a few topics in this small volume. Nevertheless, we hope that our readers find the five papers assembled in this volume to be interesting and thought-provoking. Two of the papers address issues surrounding exchange traded versus conventional mutual funds. Two papers provide updated perspectives on how to measure fund performance and what to infer from these measures. The final paper examines the relation between a set of sector funds and the corresponding underlying assets.