The study covered mutual fund expense ratios (not including market impact costs) and the behavior of these ratios with respect to mutual fund complexes and individual product lines with various amounts of assets under management. In particular, the study covered all 533 mutual fund complexes that existed in the United States during the years 1990 to 1994, encompassing assets totaling about $2 trillion at the end of the period. A mutual fund complex is a "sponsor" which may offer anywhere from.
