Offer your thoughts or opinion on the input financial query or topic using your financial background.

Vanguard ETF vs mutual fund
One reason is that it is not possible (at Vanguard and at many other brokerages) to auto-invest into ETFs.  Because the ETF trades like a stock, you typically must buy a whole number of shares.  This makes it difficult to do auto-investing where you invest, say, a fixed dollar amount each month.  If you're investing $100 and the ETF trades for $30 a share, you must either buy 3 shares and leave $10 unspent, or buy 4 and spend $20 more than you planned.  This makes auto-investing with dollar amounts difficult.  (It would be cool if there were brokerages that handled this for you, for instance by accumulating "leftover" cash until an additional whole share could be purchased, but I don't know of any.) A difference of 0.12% in the expense ratios is real, but small.  It may be outweighed by the psychological gains of being able to adopt a "hands-off" auto-investing plan.  With ETFs, you generally must remember to "manually" buy the shares yourself every so often.  For many average investors, the advantage of being able to invest without having to think about it at all is worth a small increase in expense ratio.  The 0.12% savings don't do you any good if you never remember to buy shares until the market is already up.