performers fall in the top half of the sample in the fol- lowing period, while 63.4% of initial bottom-half performers fall in the bottom half in the following period. This evidence is consistent with the notion that at least part of a funds performance is a function of skill as opposed to luck, so that relative performance tends to persist from one period to the next.4     3 William N. Goetzmann and Roger G. Ibbotson, "Do Winners Repeat?" Journal of Portfolio Management (Winter 1994), pp. 9-18. 4 Another possibility is that performance consistency is due to variation in fee structure across funds. We return to this possibility in Chapter 12. I. Introduction 4. Mutual Funds and Other Investment Companies The McGraw−Hill Companies, 2001           CHAPTER 4 Mutual Funds and Other Investment Companies 121     Table 4.4 Consistency of Investment Results   Successive Period Performance   Initial Period Performance Top Half Bottom Half   A. Goetzmann and Ibbotson study Top half 62.0% 38.0% Bottom half 36.6% 63.4% B. Malkiel study, 1970s Top half 65.1% 34.9% Bottom half 35.5% 64.5% C. Malkiel study, 1980s Top half 51.7% 48.3% Bottom half 47.5% 52.5%   Sources: Panel A: William N. Goetzmann and Roger G. Ibbotson, "Do Winners Repeat?" Journal of Portfolio Management (Winter 1994), pp. 9-18; Panels B and C: Burton G. Malkiel, "Returns from Investing in Equity Mutual Funds 1971-1991," Journal of Finance 50 (June 1995), pp. 549-72.   On the other hand, this relationship does not seem stable across different sample peri- ods. Malkiel5 uses a larger sample, but a similar methodology (except that he