ETF effects: The role of primary versus secondary market activities

Abstract

High-frequency traders (HFTs) dominate secondary market trading in exchange-traded funds (ETFs) but do not engage in ETF arbitrage. By contrast, primary market arbitrageurs enforce the law of one price, but their activities are infrequent and limited by arbitrage costs. We find that primary market activity is associated with increased volatility and illiquidity in overweighted ETF constituent stocks, while HFT activity is linked to narrower bid–ask spreads. Using a quasi-natural experiment in Japan, we show that while ETF primary market activity can temporarily disrupt market quality, the liquidity benefits of secondary market trading ultimately outweigh these negative effects.