You cannot buy and sell the exact same security, or it is subject to wash rules. You can buy very similar securities, as noted by secondcor521. At Vanguard specifically, investor, admiral, and ETF are different classes of the same thing, so you would need to change fund names. You could switch from Wellington to Balanced, or from S&P500 to Large Cap, and be safe. The basket of stocks is just different enough to be different, but the general class of investment is essentially the same. An equivalent to Total stock is 65% large, 25% mid cap, 10% small cap, so switching to just S&P500 changes your assets a bit.