Also, keep in mind that while the holding period for the wash sale rules is 30 days, Vanguard's frequent trading policy will require you to wait 60 days before moving back into the original fund (but, if you really want to, you can get around this longer restriction by submitting your exchange request by mail instead of doing it online). See here for details: https://personal.vanguard.com/us/whatweoffer/overview/redemptionpolicy