I have various tax advantaged accounts where I have Vanguard mutual funds (Total Stock Market, Total International Stock Market, etc.). However, I noticed that Vanguard's ETFs generally have (slightly) lower expense ratios than their mutual funds. Is there any reason not to exchange my mutual funds for their ETF equivalents?
It won't be a taxable event because the transactions would occur in tax advantaged accounts. Plus, I'd have lower expense ratios after making the move. The only downside I can think of is behavioral: Some would argue that it's advantageous to *not* be able to do the within-day trading that ETFs allow.
Is there any downsides that I'm not thinking of?