There has been a long discussion in the literature on the potential risk alleviating role of investment banking activities. In this paper, we assess the risk effect of US bank holding companies involvement in classical investment banking activities. A novelty of our framework is the extension of the existing classification of commercial banks' securities activities by including fiduciary activities in addition to securities trading and underwriting. Using a dataset including 436 US bank holding companies for the time period 1992-2004, we employ a two-factor model, decomposing bank total risk into market and interest rate risk. We find that securities trading significantly increases total and market risk, while alleviating interest rate risk. Underwriting activities significantly reduce total risk and market risk but show no significant impact on interest rate risk. Fiduciary activities exhibit no significant influence on the total risk. Thereby they significantly increase a bank's market risk and reduce the interest rate risk.