Tax wash sale rules prohibit the recognition of capital losses when substantially identical securities are sold and immediately repurchased within short windows. This study examines whether institutional investors use exchange-traded funds (ETFs) to circumvent wash sale rules. Consistent with tax-motivated demand for ETFs, incumbent ETFs both create more shares and experience more trading volume upon the introduction of nearly identical ETFs, particularly when recent returns are negative. We show that tax-sensitive institutions’ investment in highly correlated ETFs has proliferated in recent years, exceeding a quarter of their assets under management. Furthermore, tax-sensitive institutions holding more ETFs are significantly more likely to engage in swapping nearly identical ETFs. This swapping behavior has become widespread, with tax-sensitive institutional investors swapping $417 billion of nearly identical ETFs since 2001. We estimate that tax-sensitive institutions realized more than $84 billion dollars in losses in highly correlated ETFs associated with the swapping activity since 2001.