Purpose The objective of the present study is to examine how domestic and foreign exchange traded funds (ETFs) tracking Indian equities affect the return correlations of their underlying constituents. Further, this study investigates how these effects vary between periods of turmoil and calmness in the financial markets.Design/methodology/approach The study is based on quarterly data for stocks comprising the CNX (CRISIL NSE Indices) Nifty 50 Index from 2009Q1 to 2019Q4. The data on holdings of 45 domestic and 196 foreign ETFs in the sample stocks were obtained from Thomson Reuters’ Eikon. The paper employs a panel-regression methodology with stock and time fixed effects and robust standard errors.Findings This study documents that irrespective of the market conditions, foreign ETFs, particularly those from Asia–Pacific and European regions tend to exacerbate co-movement. Conversely, domestic ETFs lower co-movement in stable markets but during periods of turbulence a jump in return correlations is observed.Practical implications The results have important implications for ETF investors as well as market regulators because an increase in co-movement would reduce the diversification benefits of ETFs, thereby nullifying the biggest advantage that ETFs have to offer.Originality/valueThe literature on the economic impact of ETFs is highly skewed with the majority of the studies focusing on developed markets. To the best of the authors’ knowledge, this study is the first one to empirically examine the impact of ETFs on the return co-movement of an emerging market. Furthermore, the study is unique as the authors investigate how the effects of ETFs vary in turbulent and tranquil markets.