Purpose: The purpose of this paper is to study if actively managed exchange-traded funds (AMETFs) and actively manager mutual funds (AMMFs) are complements or substitutes. It also tests if there are tax or liquidity clientele effects. Design/methodology/approach: The study investigates the relation between individual AMMF flows and aggregate AMETF flows as well as individual AMETF flows and aggregate AMMF flows. A 2013 tax change is used to analyze if a tax clientele effect exists between the AMETF and AMMF markets. The authors use differences in investor groups for institutional versus retail fund share classes to test for liquidity clientele effects. Findings: The authors find that equity and mixed AMETFs and AMMFs are substitutes, although not perfect substitutes. Taxation related differences between the two products creates a clientele effect for fixed income and mixed funds where tax-sensitive investors are more likely to substitute AMETFs for AMMFs surrounding tax increases. There is weak evidence that institutional investors may prefer AMETFs more than retail investors because of their enhanced liquidity. Originality/value: This is the first study to investigate the flow relation between AMETFs and AMMFs. The fast-paced growth of the AMETF area coupled with the substitutability between the two products and tax advantages of AMETFs has the capability to gain significant market share from AMMFs in the future.