AbstractThis study examines the mutual fund market in Spain from the point of view of management and custodial costs. For this purpose it estimates functions explaining these fees using ordinary least squares and panel data. The results confirm that the most relevant factors in determining the management fee are the risk incurred by the managed portfolio, the level of its cash holding, and the number of shareholders in relation to the size of the fund. In addition, it highlights two aspects of the Spanish market with respect to the results obtained by similar studies in the North American market and in some European countries (Finland, Italy): first, the lack of a learning curve reducing operational costs, and, second, the lack of economies of scale in the management costs. Copyright © 2009 John Wiley & Sons, Ltd.